Welcome to the wonderful world of being anything but a BRD, RNG, BLM, WHM, RDM, PLD or NIN.
My advice to you would be to try and make friends with people on LB1 hunts, maybe help out other people with some Missios and try and get a static party going. If that sounds like too much work, then shift your focus instead of waiting for an invite, to making your own parties and trying to get them rolling.
If you can make nice with a couple of WHMs, RDMs, etc, you can hit them up when you guys wanna exp. They'll want to group with you because they know who you are and know you to be reliable, and vice versa.
Honestly, this stage of the game is based heavily on who you know and how you interact and behave with other people. Don't be scared to make friends with people, sure, there will be some rude people, or some people who don't want to reciprocate, but most people on this server are generally nice and helpful people, so...yeah.
Make groups, make friends and just make a name for yourself. That's how you avoid LFG for 6+ hours. ^^