LEVES
-Save up levequests
-Have 16 leves already completed before maintenance goes down, so you cann turn them in for some fast exp on a job
-Precraft items to turn in for crafting/fishing leves after your initial 16 have been turned in for DoW/M exp

RETAINERS
-Send retainers out on the highest 18 hour venture they can, you'll want them leveling fast too.
-Have 200+ Ventures ready so you can level them quickly using Quick Ventures (quick ventures reward up to 500k exp)

BEAST TRIBES
-Have a full set of Beast tribe dailies already completed for another fast turnin of exp
-if leveling DOH, do Ixalis. They will be worth ~250k+ exp per day
-stock up on Moonstones from them also, and trade them to Talan in RT for Better Crowned Pies. That Spiritbond food buff will help with getting Grade V materia

STOP DOING THIS
-leveling classes that you won't be playing for a while, save all that rest exp to get your main to 60
-leves/fates/dungeons/crafting/gathering........stop all of this on Tuesday the 16th, so you will still have the exp bonuses from the Challenge Log (only applies to early access)

CHOCOBOS
-if you're rank 20, consider getting some Thav Onions now, just in case they'll still be used to rank up the chocobo >20
-set your current favorite food to Curiel Root for the extra exp gains
-get a stack of Ghysahl Greens, with as 'hard' as the open world mobs are supposed to be, you might be using and losing your bird often
-also have the challenge log ready to go for ranking 'bos if applicable

FCs
-start saving FC credits now, you should be running double buffs 24/7 in the first month of HW. Battle exp, food buff duration, and Spiritbonding will probably be the most popular
-get donations into the FC chest of gil that will be used to fund the building of the FC airship
-discuss which members of the FC plan on leveling certain DoH/DoM. I recommend using the Short Messages to record this info.
-get your gardens empty, there might be new crops that you simply 'must have'

REAL LIFE
-fornicate copiously with your significant other, or self as applicable, prior to commencing HW activities. It may help reduce distraction occurrences later
-stock up on hot pockets, energy drinks and diapers
-take time off from work. Just don't tell them it's so you can be server first something in an online game, unless they already understand where your coming from....unless you fear they may try to beat you at it
-get nice and drunk, and sleep for at least the entire duration of the pre-launch maintenance time. It might be a while before you can do that again