I'm a little different, in that I look for domains covering subjects which actually interest me. I find it much easier to build a website and write articles on things that I'm genuinely into.
I do have some sites for completely random subjects, but my most successful ones are all based on an interest in the subject.
Look for domains for sale that are in your nichePlease list below the things to look for when buying a domain.
1. Search volume for a specific keyword.
2. Price per CPA/CPC/CPM of a specific keyword
3. Parking Revenue statistics.
4. General demand for the specific keyword.
+ many more factors