Welcome to R2R! Here is a great place to start!
The Supreme Guide To Setting Up A Saltwater Reef Aquarium Introduction The marine environment is one of the most complex systems on the planet. The aquarium you are about to set up is only a tiny sliver of the vast ocean, but it is nowhere near simple. This task is going to take patience, a...
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Any of the other sticky threads at the top of this forum will be helpful too!
That will be much more comprehensive than anything I can come up with off the top of my head... but as for stocking-
My favorite fish for cleaning the sand is a diamond goby. Very hard worker, have to mention it since it’s featured in my profile pic.
Clownfish of course are an easy choice- easy to keep and very hardy. Stick with oscellaris (Nemo) or skunk clowns, other types can be aggressive.
Start with smaller and less aggressive fish and work your way up slowly from there as they become established.
Most fish websites have a “beginner fish” section that suggests easy-to-keep varieties to think about. However, you’ll likely see those fish in the aquariums of all kinds of people here from beginner to advanced aquarists and probably won’t regret starting with them.
I also love tangs and everyone seems to want one so I will give you the most general advice I can- in your reefer 350 I would imagine you could have one of basically anything in the ctenochaetus (not sure on spelling) family, aka bristletooth tangs. Beyond that opinions vary as far as space that tangs need but most would agree a tomini bristletooth or a yellow eye kole tang (also a bristletooth) would do well in a tank that size. That’s probably a fish you want to wait a while and add last though when you have some experience, since they can be territorial.
Good luck! You found the right place to start.