You can grab some striking dummy time to refresh yourself on your skills, then try a few dungeons to make sure youre back into fighting shape. Mentioning that youre returning/new to the dungeons will usually buy you some leeway with people, but you could also start at lower dungeons and work your way back up. While youre doing this, figure out exactly where you left off in the MSQ so you can pick that back up. A lot of things will still be gated behind completing those quests(including the expansion, assuming you bought it). For gearing up, most level 50 content will give you tomestones of poetics these days, which you can exchange for i120 gear in mor dhona(if you have a ton of them, you can also upgrade said 120s to 130s). Otherwise, theres a set of 115 crafted gear you could potentially buy or get a crafter friend to make you. This gear will all be replaced by the time you get to the mid 50s anyway, so you dont have to go nuts. Your weapon plays the biggest role in determining your damage output, so focus mostly on keeping that one up to date and you should be more or less fine. Also, enjoy the upcoming story. Beating the ultima weapon was just the start, youve got a few more big story moments in your future.

Oh, and have fun! Cant forget that.