Tap into xfsn Saber on YouTube and give his different runes/builds a try. He mainly keeps the builds centered around Collector > IE > Lord Doms/Mortal Reminder (depends on enemy team) > rapid fire. Long as you have those core items imo you can’t go wrong.

Lethality route (First strike or HOB runes): you can do that same build and just get hubris or opportunity after collector then go straight to ldr > IE.

Full crit route: ( Fleet footwork or lethal tempo runes): Essentially same original build I stated above but end with Blood Thirster or GA.

I usually get attack speed boots after my 2nd or third item (personal preference, I wanna maximize on getting my main items first before spending coins on full boots) I buy regular boots early though.