You must use condoms all the time when having sex. If your partner refuses, ask your counsellor or your support group members for advice.
Also try to live a healthy lifestyle. You can eat all the foods you've always eaten, but make sure you eat regularly. Try to eat at least 3 meals a day as well as some fruit, yoghurt, sour milk or mageu in between. Also try to eat lots of protein, like meat and beans.
Drinking alcohol weakens your immune system and isn't good. If you're a smoker try to stop or smoke less. Take some time to exercise and to relax!