Tanking anxiety

I have been playing WoW on and off since 2006 and have mostly just played DPS in dungeons and raids, but with the high wait time for DPS right now I started lvling my VDH and am now able to tank LFR liberation but every time I go to queue I get anxiety about it since I've never tanked a raid before or a mythic dungeon for that matter. Any advice to get over this would be greatly appreciated.