The first point, Jerry, is that you shouldn't be flying above all that cloud anyway! And if you are, you will learn the golden rule very quickly... there is alway a hole over top of the DZ.
The Garmin 3 are a very popular unit, not just in skydiving but in most pilots flight bag. And for the useful advise, read the operating manual.
Having an instrument rating helps, as you can easily understand radials, bearings and tracks.If you don't have one, you'll learn it all soon enough. Don't place complete trust in your new friend, as they can run out of batteries and or RAIM, and then when you are on top, not knowing where that mountain is, you are up a creek without a paddle.
Program in helpful way points, or danger zones. If you know where there is a mountain peak, perhaps place it on the moving map, so you know to stay away from that area when descending.
Remember SITUATIONAL AWARENESS is the key. Never forget where you are. It is difficult when first starting off in a new area. If you're up north, then the wet will make it more challenging.
If you are not comfortable with flying in particular weather, SAY SO!!!! and don't go. I have known people who have flown in to the side of mountains in bad weather. Don't worry, the hours well come, eventually.
Be alert, and learn the area in which you operate thoroughly.
It wasn't that long ago I was also beng given this advise from over ppruners.
Best of LUCK,