Guys and girls, I need your help!?

I want to reinvent myself this summer! I'm currently trying to lose 20 lbs to get back to the size I was a few years ago. But other than that I want to know what guys find most attractive in a woman, especially in the summer. I want my boyfriend to look at me one day and think WOW he has hit the jackpot. Granted he thinks I'm beautiful and I'm not unattractive I just need a change. Suggestions please!