Welcome and have fun.
Most important tip, Take your time, ask questions and research all livestock you want to get thoroughly.
Make sure you get your tank cycled BEFORE you put livestock in it.
Don't go for short cuts.
Don't take your LFS's (local fish store) word for anything always verify it until you know you can trust them. Some are crooked, some are not knowledgeable.
The easiest way to cycle a tank is to simply throw a piece of raw table shrimp in let it decay, the bacteria you need will grow, you don't have to go out and by bottled bacteria.
Use RO/DI or distilled water to mix your saltwater mix.
You will need something to measure the salinity or Specific gravity of the water, A Hydrometer or refractometer will work.
Get test kits for pH, Ammonia, nitrite and nitrate you will need them to tell when the tank is cycled. The API Salt Water Master Kit has all of these.
Most of all be patient.