I always try to rush the center (as much as I can rush with a .52 Gal Deco, it usually works best on Port Mackerel because I can sends Seekers along the corridors and follow behind them to recharge, move forward and see what happens to my bomb at the same time, it usually works pretty well at moving quickly). Sometimes I play Krak-On Splat Roller and beeline toward the center, creating an ink-trail for my teammates to use later if they want/need to.
Exceptions to this strategy are Blackbelly Skatepark (I don't have a consistent opening move here; sometimes I beeline toward the center, sometimes I ink the right corridor and possibly take out the roller that went there too, sometimes I ink that left area and go from there), Saltspray Rig (sometimes I head to the higher area, sometimes the lower area, sometimes I jump down and ink the walkway to the lower area and intercept someone going to ink the lower area; this one doesn't really have a center, so I'm not sure what the best move is here) and Walleye Warehouse (going into the center always ends in getting splatted, so I ink either the left or right pathway before joining the fight.
Also, sometimes I put on a bunch of Special Charge Ups (they have other stuff too, but mostly Special Charge Ups) so I can get an Inkstrike (or Kraken, when I'm rolling with the Krak-On Splat Roller) and launch that before I join the fray (or join the fray as an invincible Kraken, which always fels good). This doesn't work as well on Walleye or Saltspray as I'd like, so I've been considering doing this with a Bubbler-having weapon too, but I'm not sure which one to go with. Maybe the Splattershot Jr?
Probably not the best way to open up a match (maybe I'm overextending? I tend to do that), but I think it generally works for me since I generally use shooters like the Gals or the Aerospray RG in Turf Wars (Aerospray RG is surprisingly effective in firefights, especially up close) or the Krak-On Splat Roller (I feel like I should try to take the lead more when I use rollers, since I'm spreading ink by moving).