Go to the Training Arena.

Seriously, though, it really depends on so many things. Do you have altitude you can trade for speed? How far away is your wingman (You *do* have a wingman, right?) If the bandit is already camped on your six at 1K and closing, it may already be too late. So you may have to look at how you got to that point. And the FW-190, the Bf-109, and the P-51 each have unique strengths which may allow you to escape. But again, it depends on so many things not mentioned in your question.
So, flip as it might have seemed, the rejoinder, "Go to the Training Arena" is probably among the best answers (and there are many!) to your question.