Starcraft – Galaxy Editor change map lighting

Balance is most important. Don't give someone a better start location than others.

This could include better choke points, better expansions, closer to rich mineral nodes.

Besides that, generally, modern maps have a main base, and a slightly less defendable expansion, but that's not necessarily required.

Did you increase the number of players to 8? (via the game options, not by simply placing 8 different start locations)

Did you make any changes with triggers? (Melee initialization is what's done on all new maps, which is exactly what you want, so if you changed it, your map won't work as you'd hope)