My voice hurts when I speak. What should I do?

I'm trying to correct my vocal technique, and I just tried a whole bunch of different things with my voice for more than 3 hours. I did the same yesterday. I'm definetely onto something in terms of correcting my breathing technique, but I definetely strained everytime I tried to hit a really high note the "wrong way" (with improper technique). I've read so much about vocal nodes that I'm scared. How can I protect my voice from damage?