Don't use sandpaper perches. They're bad for their feet, and can cause sores and infections.

I usually trim my birds' nails myself. You have to be VERY careful and trim *just* the tips. Birds do have blood in their toe nails, so if you do it wrong, you could really hurt your bird badly. If you haven't done it yourself before, or don't know anyone who can do it safely, then you should probably get it done at the vets. My birds are very tolerant and allow me to hold their feet and toes while I trim their nails, so its easy for me. My friend's mom taught me how to trim their wings and nails myself. I don't know if Charlie would let you hold her feet, but even if she would, it can be dangerous if you're inexperienced on this issue. I'm not sure how much vets charge to trim nails, but I know they do it.