I have a math Ph.D. but my knowledge of combinatorics sucks and I simply don't know how to compute anything more complicated, i.e. what happens when we put restrictions on the allowed configurations etc.
What I'm working on currently seems to require increasing sophistication in combinatorics (complicated word problems etc.). Can anyone recommend any nice starting points. I don't mind compact rigorous books, but they should give a broad enough overview and not focus on just a few things.