Building on this post by Richard Hahn: don’t work with a statistician so you can do fancy statistics. Work with a statistician so you don’t have to do fancy statistics.

A statistician can help design a study such that almost no statistics are needed. On the other hand, after the fact, they can at best try to do some statistical heroics (and it usually won’t be fun for them), and at worst, in the words of Fisher, a post-mortem.