I just save ideas for a new outfit in a word document on my computer's desktop, since I'm always on my computer and it's easy for me to reference. I also save inspirational pictures to a folder only for inspirational outfits. But honestly I don't use these much, and tend to just think up an outfit while I'm in the shower
In terms of switching things up, I would try pulling out some of those items and trying them on with other things. So if there's a skirt you only wear with one specific top, put on the skirt and then try on every top you own that could possibly go with the skirt. Obviously this is something to do when you have some extra time, not 5 minutes before you need to leave the house.
I think finding combos also becomes easier after some closet editing - I need to be able to not only see everything I own, but to have a pretty good knowledge of what I own in order to make new outfits. It takes a lot of work to have a fully functional wardrobe.
There are also some women (I think Taylor is one of them) who like to find the best possible pairings and then keep and wear those clothes in sets. I'm going to do some searching and see if I can find the thread where this was discussed...
Edit: this thread should be helpful, it's where Taylor and many others discussed their strategies for creating outfits: http://youlookfab.com/welookfa.....-an-outfit