How many colours can you get away with before it looks like it belongs to Mr Tumble?

Well, well, well, when we speak about color, you already know how I think about: go for it!!!

And honestly, there is not one single rule to follow, it almost depends on you, your taste and your expectation, but also on your ability to deal with different tonality and accent.

Personally, if you just start experimenting with color I would suggest to start with a neutral, vague tonal theme, maybe declined in some bright or darker tones. In this way every room will have a continuity. Use indeed bright colors to highlight some details like windows or door frames, or some niches. 

Neutral tones as a base allow you always to add anything you want, are like white paper or canvas. So if you are moving the first steps into the colour and painting world, my suggestion is to support yourself with this sort of comfort  zone you can play with. The sooner you become more confident and have more practice, so go for bold colors and accent tones.