There is a lot of articles, presentations about Software Performance Engineering Methodology. Just google it using, say, “Software Performance Engineering” and have fun.
So I won’t repeat all the things the search engines can find for us ;). Let me just outline several points, which are the most important from my point of view.
If you read my previous posts you had a chance to note that each of them was devoted to a specific technical question or story. Moreover, each of these posts contains enough technical details to help you resolve a similar issue. And what is important to say I consciously avoided general and unspecific talking without examples. Hopefully, this saved your time as you can apply my solutions without repeating my steps to find them :).
However, just a technical advice doesn’t guarantee your task resolution.