I think it was mostly just that I lucked into winning all my placement matches and started high to begin with!
In Turf War I generally use guns (?) with a high rate of fire (so Splattershots, Aerospray, N-Zap, Splash/Sploosh-O-Matic, Dualies).
Though I like experimenting*, too, as I’d like to be reasonably proficient with most weapons (helps in Salmon Run, haha).
Ability wise, yeah, Ink Recovery and Ink Saver (Main) and throw in some stuff like Quick Respawn and Last Ditch Effort.
*except with rollers, which I despise (because I cannot for the life of me use them well).