in my 39 litre saltwater tank I have 2 clown, a puffa, an angel and a star fish. The filter that is attached is not good enough to keep corals happy but the morphs are doin great. there's also 3 hermit crabs and 2 snails but they are the clenup crew
for the 1st salty tank 3 fish will be a good number. after you learn what all the changes in the tank mean like the colour of the algea. some are good and some are bad. most grow to 1 main condition. Salinity is another big one. After you have mastered all that you might be able to get another 1 or 2 fish but thats it.
I personally am waiting for some cash to appear so I can set up a 3 footer as a marine tank. Bigger is sooooo much easier but sooo much more expensive.
short version, go with 3