Once you have the tank, you might want some decorations for the turtle to hide in if it is shy or feeling like it is frightened.
If you want live plants, note that your turtle may eat it, so make sure the plants aren’t poisonous. Plastic plants are a good alternative if you don’t want to clean up after your turtle.
Putting gravel on the bottom of the tank can sometimes be a bad idea because the turtles’ food can look like it.