I have a Surface Pro 3: Now what?

I am an alien when it comes to Microsoft's products/services. I just got my Surface Pro 3 earlier today and I'm determined to give a go. I had a Surface 2 at one point but returned it within a week, since it didn't fit my needs.

Anyway, I'm loving it so far, but I don't know where to begin? Apps? Must haves? Accessories? Tips for getting the best experience? Thanks!