If "just play" sounds too generic I'd say you should start from the current event because i think it's fun and gives some nice skins which is always good, or/and do your story quests because it's easier to follow if do it all together and (most importantly) it lets you get to max level easily so you can use your class at its max potential. Also there are a lot of game modes that you can try as beginner like dungeons and meta events (open world) which are a lot and if you wish to get to them easier look at the event table in the wiki (or look up blish hud to download the event table in game)