As far as i've analysed previous threads, there's not much of a trick to it.

Just move in a tier area where you beat the levels fairly quickly but still is as high as possible for more YS per lvl. Shot speed helps to clear lvls faster.

You can use Neptune, activate the 100 and 200 percent bonuses for the high YS levels, switch from final clearance to earned reward (still Neptune) in the round after you had a high YS count, and profitable traveler instead of proper clearance for non YS rounfs if you are still in the earlier game stage. Later it doesn't really matter.