If it's a melee like me I tell em follow my lead. If it's ranged I te them what priority targets to watch for. If it's a tank I give Debuff and Tank Buster Warnings. I give those and AoE Warnings to new healers.
And even if everyone has run it I always make sure everyone remembers wonky mechanics like Belladona's Seduce in Arbotium.
A few seconds spent on the front end tends to save minutes on the back end. Not to mention it's only polite to see if everyone is on the same page.
