Step 0: Unequip your primary and melee weapons. You aren't gonna use them. (Optional)
Step 0.5: Equip a good damage dealing secondary.
Step 1: Always be on Merulina.
Step 2: Always be moving (for dat 200% crit chance bonus boiiii).
Step 3: Use your 1 if you're in trouble (and Gloom if you need heals).
Step 4: Murder shit.

If you don't think you need Gloom's heals, then you could opt for Resonator for crowd control.

This build is works on steel path. Less so than other frames, but you're playing Yareli for the k-drive experience and not to be the most effective frame out there. As for non steel path missions, you're good.

It is worth noting that [Yareli] is really good versus infested. Like, really good. She is straight up immune to some of their shenanigans (not ancient disruptors sadly). Anyway, I highly recommend you use her versus infested, steel path or otherwise.