This guide is for those who enjoy playing Final Fantasy XIV, but don't have too much time to put into it, want to play what they want to play in the game and not what the game thinks you should play, and spend more time playing other games, or with their partner, family, practicing kendo, eating out etc etc. Yes, you. No, not you, her next to you.
This guide will begin with the simple things you probably already know and get to the real advice at the end.
UP TO LEVEL 60 / ILVL 145
There are many guides already available, but you should use this time to read up on your job and practice the skills as you acquire them. Make sure to unlock and try all the content you can at your own pace, take your time, listen to help given by others, don't let the people with anger issues get you down, and hopefully by the end you should mostly have enough Level 58 gear and a piece of Law to get you to buy cheap FFXIV Gil. Ignore Coil and the Extreme primal fights for now though, you can come to those later. This will probably give you two to three months of great content at a gentle pace.
LEVEL 60 / ILVL 145 to 170
Welcome to the endgame, because by now you've cleared all the story content and now you can spend your time repeating what you enjoyed and getting your playing ability up to the level needed for the harder challenged. Remember that at Level 60 how you play your job is radically different from 1-59 in many cases, so read the guides, practice against dummies to start and then use the other content to perfect.
The next stage to unlock more content is iLvl 170. This is really quick and easy to reach. You will need to buy equipment using Tomestones of Law from Hismena in Idyllshire(5,5). Tomestones of Law drop from all roulettes in plentiful supply, as well as hunts and pretty much everything else you can do. The best roulettes to run are the Expert and Level 60 ones, which you can also run with friends, as they drop Esoterics too, and are the slightly more tricky dungeons in order to practice your hand at while you're still learning your Level 60 rotation and abilities.
LEVEL 60 / ILVL 170 to ILVL 200 and beyond
So, now you have a full set of iLvl 170 (almost). You will need one extra item to offset the single iLvl 160 ring you probably still have, which you can buy with Esoterics. You should ideally be saving your Esoterics for the iLvl 200 weapon, as this is the only thing I'm going to recommend buying with them, but if you're in a hurry you could buy a iLvl 200 ring first which will get you over 170 which is required to enter Alexander (normal).
Once you have iLvl 170 then you can enter Alexander (normal). This is an incredibly efficient way of going from iLvl 170 to iLvl 190, and you can now run it as many times as you like.
Once you have iLvl 175 you can enter the 24-man raid Void Ark and at iLvl 179 you can enter exploratory missions. The Void Ark can provide one piece of iLvl 200 (Esoteric level) armour per week (no weapons or accessories) in one drop, if you're lucky enough. Exploratory missions have promise too but we don't know much about it yet.
Use any spare Esoterics you get after your weapon for Cheapest FFXIV Gil, as you have no other sources of iLvl 200 accessories. After you have full iLvl 200 weapon and accessories, use any remaining for that final piece of iLvl 200 armour/clothing that annoyingly just won't drop from Void Ark.
Congratulations, you're now iLvl 200 without too much grind.
THE TICK AND THE TOCK
Now are the key points about what you can do and what you should do. Before we proceed you need to understand how the game patches work. In reality the game works in six month cycles, each six month cycle consists of two major content patches, one at the start (the tick) and one after three months, half way through (the tock). At the start of the six month cycle they introduce gear at 20 iLevels higher than it was previously, making much of the previous redundant. In short, if your main focus is gearing up, your efforts will be largely reset every six months. Understand this to avoid future frustration.
At every tick and tock Square makes equipment at a level that was available three or six months previously quick to get, and introduces new equipment that again takes a very long time to get. Get the former, avoid the latter.
I have highlighted in bold the tasks that are time efficient and you should do at each stage and in italic those you should avoid. You should get enough stronger level tomestones (Esoterics) for the weapon, even though esoterics are in italic, but it won't take long for just this one item and will get you good practice at the latest dungeons without going overboard.
The tick (last tick was Heavensward launch)
iLvl 170/180 equipment is easy to get (Law tomestones)
iLvl 190 equipment is easy to get but only one a week (Alexander normal)
iLvl 200 equipment requires timesink (Esoteric tomestones)
iLvl 210 equipment requires clearing of very hard content inaccessible without some iLvl 200 equipment and a lot of time, effort and skill (Alexander savage)
The next tick in Feb 2016
iLvl of top gear goes up by 20-30 iLevels
weaker Tomestones (Law) are made redundant, stronger Tomestones (Esoterics) take the place of law, and a new stronger Tomestone takes that place
new super hard content introduced (Alexander savage phase 2)
weaker version of super hard content introduced (Alexander normal phase 2)
The tock (last tock was today, 10th Nov 2015)
iLvl 190 equipment is easy to get without best ffxiv gil seller (Alexander normal)
new iLvl 200 equipment is easy to get but only one a week for the first month or two (Void Ark)
iLvl 210 upgrade for any Esoteric equipment that you have is much easier to get (although not the Esoterics themselves)
The next tock is in May 2016
new casual 24-man content is introduced
upgrades to the stronger tomestones (whatever the replacement for Esoterics is) become reasonable to get