You definitely want to take DG's advice. Start with someone outside the hobby you are comfy with. This will give you a chance to figure out how to mentally, then physically relax first. Lots and lots of lube. Also, you have to know whether your digestive system is going to behave or not, and adjust your prep work accordingly.
Requirements:
Relaxed mind
Relaxed body
Clean pipes
Tons of lube
Digital warm up
Toy warm-up
Do not proceed until you are to the point that the toys are actually an enjoyable feeling for you.
Eventually a pro (like me...lol) doesn't need warm-up, just lube. When it's time, I just use my Jedi powers to relax my body and enjoy