Have you read Patterns of Enterprise Application Architecture? If so, have you referenced it recently? I first picked up the book 2 years ago and loved it. However, in the time between then and now I haven't referenced it near as much as I should have been. The good news is several of the solutions I've developed in the that time used several of the patterns Martin describes in the book. The bad news is I likely wasted a lot of development time while I was moving towards the patterns due to trial and error.
The moral of the story (for me anyway) is it's not good enough to just read a book and retain the things you agree with or like. Take the time to know all the topics discussed in the book and reference it if you find yourself in the situation where you need a pattern you weren't previously familiar with. Additionally, take the time to skim your pattern books now and then. You would be amazed how much good information seemed irrelevant the first time you read it. If you stick to the good patterns books, it's likely that every pattern has been the right choice at one time or another. You never know when a previously discarded pattern is exactly what you need currently.