Ok, I was in the same boat you are 3 weeks ago. There are loads of Noob friendly LS's recruiting and running end game content to boot. (Believe you me, when you come back you are more or less a noob again).
First, on crafting 90% of the mats you probably gathered before leaving are now only used to make "Dated" gear, and most of your gear is also probably dated as well. The upshot is that most of the "Dated" gear is Optimal level as opposed to the now more prevalent Required level and the stats are not much worse and some are better.
http://mooglebox.com/includes/ is a good source of information from gear to recipies, to gathering guides.
Second, run around the towns and gather lots of the little quests. Most reward with semi-level appropriate gear and an ok amount of gil. A lot of them are very easy to do but require a bit of a long run.
Third Grand Companies. This bit is the bread and butter right now. You are over level to start so this won't be an issue.
They are located at the Market Wards in each of the capitols. It doesn't matter which one you choose to start with because as it turns out you will have to do all of the starter quests and become a "Recruit" of each of them before you can enlist formally in one of them. The UPSHOT of this is that you get ~750 seals from each one, which is enough for a decent mid-level body piece. Which ever one you do pick to go ahead with will have a level 25 quest for you. Make sure you check some of the quest logs as they will /require/ a party to do them. Especially the ones with the capitol names in (). These babies are worth 1k seals.
Next upshot is save 2k-3k(?) (cannot remember the exact amount) seals for your chocobo license. Then you will have a mount to run around and it saves you a lot of time and the 800gil rental fee.
That right there should take you a bit and get you use to the game again.
oh and before i forget you can now hire a second retainer. Good info for all the old mats you have and anything else you want to sell.
Next Spirit Bond (SB) your gear will now "tune" to you. There is a quest you can look up on line (just google Materia quest FFXIV). It gets you the ability to turn SB items into materia. There are also 2 other quests there one for level 18+ Gathering classes, and level 18+ crafters. These allow you to bond materia onto gear. There are good guides for this on the loadstone and online.
And finally as i need to run atm.. there are Jobs now. These are unlocked by quest. They require the main class be 30 and a second be at least 15. There is a good guide for this also on the Lodestone.
Anyway, best of luck! Got to run!