I'm practicing my voice out of pure musical curiosity. I'd like to have a decent grasp on singing, but I've never really sung before and I'd like some tips on developing my singing voice. I like playing and singing along to some songs, and pitch isn't too bad for me, but I can't sing very loudly or constantly without losing breath or screwing up (or both). Any tips on building vocal... endurance, I guess? And just strengthening the whole system? Thanks.