Personally, I'd rather have a voice teacher who is objective about my singing. How can you get good guidance if they let their personal opinion color their views?
Breath is important. Always remember to breathe deep into your diaphragm. Try and stay away from caffiene. Dairy isn't good for the vocal cords either. However, I've been able to have dairy and then go sing with minimal (if any) problem, so it really depends on your physiology. Alcohol and smoking are also bad for your voice.
A bit of lemon juice mixed with water is good for your voice.
If it hurts, you're doing it wrong. If it hurts, you need to stop and let your voice coach know that it hurts.
Drink lots of water! Staying hydrated is just good for you all around.
If you live in a dry climate, you might want to invest in a humidifier. It's not fun singing when your throat is all dried out. But again, this depends on your physiology - heating systems used in cold weather dry me out, but air conditioning does not. But my boyfriend gets dried out easily when in air conditioning and heating.
You might also pick up Pro Secrets of Heavy Rock Singing. Especially if you can't afford a vocal coach just yet. It's a pretty useful book.