Open D is tuning I've been using most to get started. It's (low string/6th) DADF#AD (high string/1st).

Open Dmin: DADFAD - pretty much same as above with the F# tuned a step lower. If you happen to like tunes in a minor key, this is a nice one.

Open G: DGDGBD

DADGAD isn't open tuning, just a versatile one a lot of people like.