These are just common builds, I am not a Yorick great sadly.

Of course the Purchase Order can vary, you want to react to your opponent, early MR vs AP laner.

I run different runes, but these are not the popular set

9x attack speed red
9x scaling armor yellow
6x CDR blue
3x Scaling MR blue
3x Move speed Quint

Many people will take flat armor/MR over scaling, but scaling rewards later if you risk a vulnerable laning phase

Try to force your enemy to use their dash or blink before you cast trap if you can, otherwise it will just escape.

If you have trinity, you can cast your spells without a target to get spellblade procs on the tower if there are no enemy minions around and you feel safe enough to do so.

Your ultimate scales with both health and damage and can be a hassle for the enemy team. It is not super smart, but it is like having a 6th man when you want to contest objectives, otherwise people will just run away from it.