I know not everybody can sing well and I am including myself, but only lately have I realized that for all my life I have been belting out vocals with pure, wreck-less abandon or bombastic emotion. Emotion is good, of course 98% of the time. But if you're singing with one side of your brain (your subconscious, perhaps?) and not paying attention to what you are doing with other side (your intellect), then for me at least, my limitations will surely come into play along the way. So only for the past few months or so, I use both my head and my heart, and I have been doing a lot of critical thinking about my singing; trying different things, staying conscious of how I breathe, using stomach muscles I never used before. Identifying 'laziness' in my style (that's a big one I think), and paying close attention to pronouncement. It's paying off, slowly but surely, but it is a very repetitive process that taxes my patience, which is always in short supply to begin with.