My shortfall is desserts, particularly when baking cakes and will always follow a recipe (hence why my cake repertoire is virtually non existent)! But I'm planning on changing this fear of cake making in 2015 and be confident enough to experiment more.
However all my other recipes are generally my own. I might find inspiration from a recipe and modify it to suit my requirements (I'm vegetarian but eat lots of fish and seafood). I also try to cook non fat or low in fat and don't like to use salt or sugar in my recipes, so I'll try and find ways to substitute with other ingredients.