I came in on the same boat with nothing but fresh water tanks all of my life. Always considered dabbling into saltwater it just seamed too expensive and time consuming. Then it happened, we were invited over to a new friends home who just happens to have one of the most beautiful reef tanks imaginable, I was hooked! There are a few things I can highly recommend & would never start another tank without. One is Tropic Eden Reef Flakes for substrate, in my opinion nothing comes close. Caribsea's Life Rock is another. You don't have to worry about any bad hitchhikers, it's already seeded with good bacteria, & it looks great. Next would be a good protein skimmer, wouldn't be without one. Lastly and what I consider to be the biggest reason for my success is Marine Pure. This stuff is amazing with so much more surface area than anything else in the industry it is in my opinion unbeatable.
Good luck!