Have you already done your limit breaks? If so, I would suggest getting into a worm party in Aby~La Theine. You will probably be asked to /whm to help cure the party, but you will level incredibly fast. If you prefer a slower approach so you can try to keep you skills capped, then your best bet would be solo'ing. (most people level then go back and skillup these days).
If you haven't beaten your limit breaks, then start the Aby quest line (Joachim in Port Jeuno) to start your stones rolling, then join a GoV in Bostaunieux Oubliette. Since you will need to stop every 5 levels, it makes more sense to stay out of Aby IMO.
Edit ~ Adding this in here ~
I suggest reading up on Aby because it can be quite overwhelming when you first start in on it. You will also want to get
MM Atma before you really start doing anything inside, as the +15 refresh is insane.
I'm not sure on gear for level 70 other than
relic from Dyna, but eventually you will want to get
your AF3 set. Relic can also be
upgraded now and is pretty nice to mix and match with other pieces.
If you are serious about SMN, then you will also want to work on the Trial of the Magian staves for - pet perp and - blood pact ability delay. They allow you use your other gear slots more wisely for refresh, pet accuracy, pet haste, etc. Here is the full
staff trials link, and here are a couple of the ones people find as must haves:
Garuda Staff Pet MAB Staff Shiva Staff I would also suggest perusing
here and checking out
Pergatory's item sets.
Good luck to you!
Edited, Apr 9th 2012 10:09am by Elspetta