Just getting your feet wet and not wanting to get discouraged, I would even suggest that you skip out on the live sand and crabs. You want to make it easy to medicate, and live sand eliminates many possible medications should something go wrong, as do any inverts.
For a starter tank, crushed coral substrate & synthetic coral decorations are fine. Most algae in a saltwater tank is a result of particulate filtration, so just don't use a filter pad and your synthetic corals will go a good month without needing cleaning. You can run a filter pad 1 day per week to keep a nice polished look. I would suggest a venture powered protein skimmer (SeaClone makes a nice easy to use well priced model) and a Penguin BioWheel.
Just keep a weekly test on the Nitrates and change water frequently enough to keep them below 40 - 60 ppm
. I would guess a 10 gallon monthly water change would be sufficient, depending on stocking levels and fish size.
Most important for a beginner tank, be very very careful about what fish you purchase. Make sure they are eating well, have clear eyes, & are swimming normally in the display tank. Take them home quickly & feed the same foods they are eating at the pet shop while you acclimate them to their new home.