I've never used any, but "White box" or back-drops to help control the focus/brightness can help I hear. White boxes are basically just boxes with all white sides to provide a blank background for the photo, you could make one with as simple as a shoe box and white paper, and a good light to illuminate it. There is probably a guide you can find without much effort I'm sure.
Other than that, any picture I take is just with what ever camera I have available with the best quality. It use to be my mother's camera I'd borrow, but since Cell phones have become amazing those are my best camera. I also have never used a tripod, but I could see that being helpful, as even I have to take a handful of pictures sometimes if they are coming out too blurry for my taste (I seldom have any that are perfect), that's actually probably the first thing I'd try to get personally, although I'm not sure if that's something you'd need to buy or if you could just jury-rig a set up to hold your phone perhaps (Like when I set up models to dry glue in positions I know they may droop or fall off if they aren't held up? Just setting other models or paint pots under them).
But yeah. Mostly controlling the elements in the photo is probably the biggest thing. Making sure you aren't taking a photo in a room with extreme dark/light contrasts (Like a dark-ish room with the sun glaring in directly?) or backgrounds that are not suitable, like couch/fabrics or patterns that distract the focus of the camera, that sort of thing.