Hi there! I'm new to saltwater too but I can share some of the mistakes and things I have learned going into this hobby.
When cycling your tank the most common way to do it is with a fresh raw shrimp in a pantyhose (keeps tank cleaner) until your ammonia rises to about 4.0 and as the ammonia starts to lower, your nitrites will rise, and then lower. As the nitrites lower, your nitrate will raise. Once you have zero nitrites your tank is cycled. You'll want to do a number of small water changes to get your nitrates down.
Get a refractometer. My hydrometer was reading 0.04 lower than my refractometer came in at. They're much more accurate.
Use reef salt, rather than regular saltwater salt - it has the elements you'll need in it to grow corals if you choose to.
As for test kits the best ones (from my research) are the Salifert and RedSea. You'll need the regular pH, ammonia, nitrite, nitrate kits for a FOWLR
tank. If you want to go into corals you'll need kits for calcium, magnesium, alkalinity/KH
, and phosphates.
When cycling your tank you'll probably be testing your ammonia, nitrates and nitrates every few days or so. After that you will only need to check ammonia and nitrite if you find you are having problems with your tank. I test my nitrates every now and then - but I know when to do my water changes so they stay low. If you decide to add corals I would check the other parameters such as calcium, magnesium, phosphates, alkalinity once a week or once every two weeks. Your reef salt should maintain your levels as long as you keep up with your water changes.
Most people keep their salinity around 1.025-1.026. The latter number is the salinity of natural saltwater but many hobbyists keep theirs at 1.025.
Your other parameters should be around the following:
Nitrate: <20 (but lower if reef tank)
Phosphate: 0.01-0.08 (but not 0)
You'll figure out where your params should be over time but hope this helped a bit. Cheers.