No I do not think one can not avoid the migraines completely. It is different for everyone though. They say, for example, that at least two days a week of 30 minute exercise, is equivalent to taking a beta blocker preventative medicine everyday.
So for me, I have tried several preventative medicines, including beta blockers, however, they made me feel sick to my stomach, dizzy and even pass out a few times. So my doctor said to make sure that I keep up on cardio exercise to reduce the pain of migraines. Unfortunately, I have chronic migraine which is a migraine that is there nearly all the time and almost everyday. For me, changing my lifestyle is not about preventing migraines since that is impossible, but rather reducing the pain and hopefully the frequency.
I would say that adequate sleep (10 to 12 hours a day) and the minimisation of stress for me, personally, is absolutely key. Regular meals, avoiding trigger foods and smells (such as alcohol and perfume), regular water intake, and exercise are also important.