That's the thing with me - I don't.
I think the reason I've stayed playing this game for so long is that I really don't have weapons I stick to the most. When I play a weapon for a long time, enough time will have passed naturally for me to be interested in another weapon. Even if it's something similar like going from the Tentatek Splattershot to vanilla, I still had to learn how to use Trizooka (not that hard lmao) and get used to not having a bomb that I can roll as opposed to one I can poke over ledges with. Going from one weapon to its other kit is the absolute minimum you can do with this though.
I think it's best when you jump between weapons with completely different strengths and weaknesses to the stuff you've played recently. There was a period where I decided to jump from only really playing shorter-range stuff directly to Ballpoint. I sucked at using Inkjet, couldn't get used to the multiple firing modes, and found Fizzy Bombs awkward on the thing at first, not to mention the difficulty of someone who doesn't really play other shooter games learning how to aim at further opponents. But I thought the weapon was cool so I decided to stick to it and I actually feel fairly comfortable with the thing now. It's not my absolute best weapon but I've worked past all of those problems. Ballpoint ended up being far and away my most used weapon for like two months, and that learning curve is very fun to me.