Welcome to the forum, and good luck mining! With difficulty as it is, I would look into mining altcoins. Like mining bitcoin, it is also very speculative, though.
I'm currently looking at TomPool, they move from coin to coin for whichever is more profitable, I know litecoin I can't mine with USB erupters, which would be the next step.
Also thought I'd ask, for the USB erupters do they need to be shut off once a day or just keep them rolling 24/7?
Thanks all!