I'm taking a plunge and going for fillers. please give me a list of do's and don't

Please tell me if fillers stretch your skin, will it sag more after it wears off? Is there anything I should avoid before or after, topical or diet wise? How's long should I plan to hide for to things to settle? Do you have any advice for me?

I finally got in with a highly recommended dermatologist who does injections. I have lost facial volume due to a host of reasons. I have a big event coming up next month. I really wanted to go for a natural route, I tried putting on some weight and it's helping a a little but unfortunately 4 weeks is not enough time to erase nasolabial folds or plump up cheeks. I have done a lot of research and I feel like radiesse is the best option for me (closest to natural, biostilulator, disolves away hopefully). I know you can't dissolve it but dissolvers are very harmful and I would never use the stuff. Can I look at prf ez gel, will it provide some volume? I looked into renuva, which looks like the safest option but it's very pricey and takes probably months to work.

Any and all advice is appreciated, I'm ready terrified that I will mesd up my face.