Try the search function, using the term "paint interior". Up in the blue bar near the top of this page, one of the selections is "Search". I like the Google search in there, it's very fast and efficient.
I just tried that search, and it brought up ten pages of threads loaded with good advice.
I'm not trying to tell you to get lost, but anyone answering that question here would only be repeating suggestions from a very popular topic that has been discussed many times.
So try that, then you'll be able to ask more specific questions once you get the drift of what is generally recommended.
If it's to be, it's up to me.