Identify an edge

I've accumulated a lot of knowledge on how things work, and what to do when certain conditions are in my favour, however I suppose the challenge is knowing when to execute a trade.

I was wondering how successful traders with an "identifiable edge" found your edge. Is it a matter of data mining? Identifying patterns and back-testing to check if the validity of your (proposed) strategy? I guess I'm just asking for a map, or the starting point you use to find edge.

All comments welcome.