I'm thinking 2 flexible-shooter, 1 charger/ranged-shooter, 1 roller/assassin+coverage-shooter is ideal as a general-purpose comp.
On maps like Walleye Warehouse where there's one central hub that must be controlled, you'll want to send the first three three members to it as fast as possible and try to secure it as soon as possible. Have the last player secure the low-hanging fruit areas around the base, then a little ways in once the chaos has started unfolding and the ink patterns are getting erratic, you send them in to gank someone and turn the tide in that area. Then the first two fan out to poke into enemy territory and see where they're weak, the third sits a little behind them as backup-slash-fortification, and the fourth cleans up stray bits of enemy ink while being on call to help if someone gets jumped. If things go south, send a flex shooter in behind the enemy team to force them to back up (with the understanding they're going to die for the betterment of the team, just try to live and cause havoc as long as possible), and while the enemy team is split your defense can push them back to the central staging area.
On maps with two major asymmetrical staging areas like Saltspray Rig, you secure the more important area at the beginning in the same way, but this time the fourth player is a scout who tries to safely harass whatever enemy players go down to the bottom area. If nobody shows up there you take some for free and then ASAP super-jump to your team because they're probably pushing as four in the big area. If one person shows up you duel them. If two or more players show up, tell your team and try to keep them there as long as possible without getting yourself killed (as my childhood basketball coach told me, a double-team leaves the enemy shorthanded elsewhere). If your team is halfway competent they'll be able to secure the big area by the time you're forced out of the small one. Once the big area is secure, leave the third player nearby to fortify it while the other players spread out as normal.
Communication is vital. Remember that you can super jump at any time, not just from the spawn point. This means it's very possible to turn around a shorthanded engagement provided your friend can survive long enough.