I'm assuming anal sex tips apply here as well.
First, you'll need a douche and douche fluid. This will help you cleanse your ass.
Second, you'll need to clean it with anti-bacterial soap and warm water after each use.
Third, you'll need very good lube and use a generous amount.
Fourth, before you even think of sticking anything up there, try to foreplay with your lubed fingers to simulate your anus and let it relax. Try with small dildos before moving up larger and larger to your preferred size.
