Hi there
The setup can be pretty simple - all archerfish need is a pretty decent sized tank (I'd say 4' or 5' will do for a good sized group), brackish water and some good temperature. Allow the tank to cycle for a few weeks and you're ready to add archers. Maybe include some roots, wood, rocks and other decor for shelter so that they may take refuge as often as they feel comfortable.
If you're looking to make a setup so they can practice their shooting skills, just don't fill the tank up as much and ensure that a piece of rock or wood sticks out the water. Place insects or other food on there amd BAM. You have an archer show.
They can share a tank with several of the bigger brackish species - monos, scats, and silver shark catfish all make good additions to an archer tank, though I think just a school of 4 to 6 archers looks fantastic.
As I said earlier, keep the temperature high and also try to keep the water well filtered, especially if you're feeding meaty food like insects a lot. Archers will also take fish, shrimps and floating pellets in their diet.
Good luck