The key to successful injectables is a natural end result. So how do you accomplish that?
Stick with temporary fillers. You do not want to use a permanent or semi-permanent filler that will not age with your face.
Set a schedule. Try to be consistent. It is best if you don't "start from scratch" with each treatment
Be conservative. Ask who is injecting and how much experience the injector has with the product.
Know what is being injected. Ask about side effects, bruising, expectations. How much product is being injected and location. Your medical chart should keep a documentation of all your injections. You should be able to see the packaging and bottle that your product is coming from.