Everyone has given great advice so far! Here are some additional tips from me 
Lights: shooting using indoor lights or on days that aren't sunny is difficult and needs extra thought - but too much sunlight will also result in washed-out colours, overex-posed faces and ugly shadows. Seconding Alliecat's recommendation: cloudy-bright is the best weather for outdoor shots. When indoors, using an external light source (like a flash) will have a similar effect to super sunny weather: ex-posed, convex surfaces (like a forehead) may appear as an overly shiny reflection, while anything concave (like eyes or the area around the nose) will get extra shadows. Shadowy eye areas can make your dolls look tired or sick. Luckily though, when you are using an external light source you chose, you can adjust where the light is coming from. For starters, and without a need for further monetary investment, you can try using your phone's flash (if you take photos with another camera) or a handheld flashlight (if you shoot with your mobile), holding the camera in one hand and the light source in another - this way you can easily readjust the angle of the light source to see how it changes the shadows and thus the dolls' appearance. Try taking several photos with the lights held at different angles and study how it changes the appearance of the doll.
It's also fun to ex-periment with placing a coloured transparent layer (like a coloured glass bottle) in front of the light source. It will colour the light and will technically apply a coloured filter to the photo
Shooting using light tents or boxes will also create great photos, but for this you need to invest into an extra tool, and it's understandable that you don't want to start off spending a lot of money. Luckily there are some great life hacks out there for making your own lightbox cheap - like the one shown here, made out of a cheap IKEA laundry storage thingie - which you can even fold up when you don't use it, to save space:
https://www.flickr.com/photos/miwo76/255...otostream/
I do have one of these myself, but I have to admit that I haven't yet managed to actually try it out, so I'm not sure it fhis would be big enough for Pullips.
Posing and positioning: always shoot with the dolls standing up if that's the effect you're going for. Gravity will work against you, and the clothes and hair will give you away if you try to take the photo with the doll lying down.
As Aijo and Alliecat mentioned, adjusting settings like ISO and the depth of field can make a big difference. If you can, I'd also recommend keeping the ISO low (between 100 and 4-500) to avoid graininess - and for a doll portrait, where you want the doll to clearly separate from the background, the depth of field (a smaller number, usually with one decimal - like 1.8 or 5.6) should also be small. Phone cameras usually have this high by default, to ensure everything is in focus all at once - otherwise if you took a photo with your friends and some of them would be standing behind you, they'd become blurred out If you want to take a portrait photo though, and if you have your doll prepped up against the background, this will also keep the background in focus, resulting in a "too busy" photo in which your subject won't "pop off the background" but will rather blend in with it. It is still possible to achieve a smooth, blurred background if you cannot adjust the depth of field, but the background has to be further away. If you can't pose the doll in another way and you have to prep them up against the background, I'd suggest a less busy, already blurry, or plain-coloured background, otherwise the subject of the photo will get lost in the busy background details. If you cannot change the depth of field but you can bring your doll further away from your background, you could try the following exercise which helps you get to know your camera better, demonstrates depth of field in action, and helps you determine what level of it you prefer: stand your doll up against the background, and take a photo - then bring the doll a little closer to you and away from the background, and retake the photo. Repeat several times, bringing the doll closer to you and away from the background with each shot. With the doll always being in focus, you'll see the background starting to get blurrier with each shot. Choose whichever you like best, and take the photo you'd like using those measurements&positioning
For backgrounds I also use paper - most of my background papers are either bigger-sized scrapbook papers or A3 printouts glued on poster boards.
Lights: shooting using indoor lights or on days that aren't sunny is difficult and needs extra thought - but too much sunlight will also result in washed-out colours, overex-posed faces and ugly shadows. Seconding Alliecat's recommendation: cloudy-bright is the best weather for outdoor shots. When indoors, using an external light source (like a flash) will have a similar effect to super sunny weather: ex-posed, convex surfaces (like a forehead) may appear as an overly shiny reflection, while anything concave (like eyes or the area around the nose) will get extra shadows. Shadowy eye areas can make your dolls look tired or sick. Luckily though, when you are using an external light source you chose, you can adjust where the light is coming from. For starters, and without a need for further monetary investment, you can try using your phone's flash (if you take photos with another camera) or a handheld flashlight (if you shoot with your mobile), holding the camera in one hand and the light source in another - this way you can easily readjust the angle of the light source to see how it changes the shadows and thus the dolls' appearance. Try taking several photos with the lights held at different angles and study how it changes the appearance of the doll.
It's also fun to ex-periment with placing a coloured transparent layer (like a coloured glass bottle) in front of the light source. It will colour the light and will technically apply a coloured filter to the photo
Shooting using light tents or boxes will also create great photos, but for this you need to invest into an extra tool, and it's understandable that you don't want to start off spending a lot of money. Luckily there are some great life hacks out there for making your own lightbox cheap - like the one shown here, made out of a cheap IKEA laundry storage thingie - which you can even fold up when you don't use it, to save space:
https://www.flickr.com/photos/miwo76/255...otostream/
I do have one of these myself, but I have to admit that I haven't yet managed to actually try it out, so I'm not sure it fhis would be big enough for Pullips.
Posing and positioning: always shoot with the dolls standing up if that's the effect you're going for. Gravity will work against you, and the clothes and hair will give you away if you try to take the photo with the doll lying down.
As Aijo and Alliecat mentioned, adjusting settings like ISO and the depth of field can make a big difference. If you can, I'd also recommend keeping the ISO low (between 100 and 4-500) to avoid graininess - and for a doll portrait, where you want the doll to clearly separate from the background, the depth of field (a smaller number, usually with one decimal - like 1.8 or 5.6) should also be small. Phone cameras usually have this high by default, to ensure everything is in focus all at once - otherwise if you took a photo with your friends and some of them would be standing behind you, they'd become blurred out
If you want to take a portrait photo though, and if you have your doll prepped up against the background, this will also keep the background in focus, resulting in a "too busy" photo in which your subject won't "pop off the background" but will rather blend in with it. It is still possible to achieve a smooth, blurred background if you cannot adjust the depth of field, but the background has to be further away. If you can't pose the doll in another way and you have to prep them up against the background, I'd suggest a less busy, already blurry, or plain-coloured background, otherwise the subject of the photo will get lost in the busy background details. If you cannot change the depth of field but you can bring your doll further away from your background, you could try the following exercise which helps you get to know your camera better, demonstrates depth of field in action, and helps you determine what level of it you prefer: stand your doll up against the background, and take a photo - then bring the doll a little closer to you and away from the background, and retake the photo. Repeat several times, bringing the doll closer to you and away from the background with each shot. With the doll always being in focus, you'll see the background starting to get blurrier with each shot. Choose whichever you like best, and take the photo you'd like using those measurements&positioning For backgrounds I also use paper - most of my background papers are either bigger-sized scrapbook papers or A3 printouts glued on poster boards.
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"I wear my sunglasses at night
So I can, so I can
See the light that's right before my eyes"
"I wear my sunglasses at night
So I can, so I can
See the light that's right before my eyes"