What is cool to put in your place on roblox

Well, I'd start with scripting my own things according to what I'd build.
For example, if you're making a military game, build different guns and clothing for each team.
If it's social, build a small town for the map. Remember- ANCHOR EVERYTHING YOU WANT TO STAY THE SAME. If you don't, people will destroy your map, and each server will be a mess. You should only anchor certain things.
Good- buildings, battlefields, skateparks, gardens
Bad- the one weapon that can save you from the zombie apocalypse you accidentally created.
Lastly, DON'T USE FREE MODELS.