Write good quality stories. Some publication editors are nominated boosters, but there are more coming on all the time, so posting through publications may help. I've only had one boosted since the incentives increased. Sometimes the short opinion pieces can help get you noticed, but they won't usually get boosted. There are boost guidelines. Here you go: https://help.medium.com/hc/en-us/articles/360006362473-Medium-s-quality-standards-how-we-review-stories-for-distribution