I have musical experience - I've played the violin for 8 years and the piano for 4 years - and I'd really like to improve my singing but I can't afford lessons. What can I do at home to improve my singing?

I've had the same problem before and it works. First start off by warming up your voice. Sing in the shower in your room and whenever you can, drink water or tea so it will smooth out your voice so its not too squeaky. Then start singing a song but record your voice, listen to the singers vocals and timing, then listen to yours