Masturbation Tips

So my boyfriend and I have been together for six months, and we just got to having really good sex. We both are in Colorado for school, but I live here and he lives in Hawaii. In 3 weeks he will be going back to Hawaii for about 2.5 months. For me, I know not being with him all the time will be hard, but our relationship is great so emotionally I'm not too worried. However, I know im gonna miss our sex a ton, and I SUCK at masturbating. What are your guys' best tips to get me through the summer?