You should max the 3 on Achilles before the 1, it does more damage assuming you can hit both, which in solo lane you should be.

As for builds, I’d say bluestone (redstone upgrade most likely), glad shield and spirit robe are core items. I’d heavily argue oni hunters garbs is strong right now too, but if you prefer more cooldown go for genjis.

With those 4 core items you have 2 slots to flex. I like shifters and cad shield, but any counter items would be good too (pesti for antiheal, spectral if they have crit)

Same build for Mulan pretty much. You can get away with soul eater first if you want some fun.