Go to the loo before you do any anal play. Some people douch as well.
Defintly google anal training and get your self some butt plugs of incremental sizes. You can buy a set, but sometimes the size differences between the plugs might be really big. 1” circumference more when going up is really max (i went up in 0.5” as it was more comfy for me). 3.5” circumference is a good size to start with.
The sizes you want to be reading on the toy listings are the circumference and the length. Both effect how intense a toy will feel. As does the material (start with silicone).
Get a good quality anal lube and dont be afraid to use it. (I like sliquid sassy). Wetter is definitely better.
If you havent tried anal before, theres a ton of good info on here if you have a search. (Search bar is top right.) heres one that might help.