I personally blame a lot of the problems on ToA. With the release of ToA, experience became far easier to obtain and many people spammed jobs to 75. While the low level jobs didn't change (exp to mid-50's remained the same), people saw this as the quick method to get high level jobs and skipped all the "necessary" things such as proper equip, merits and end game. Now, most players have multiple 75 jobs and very few feel the need to level another job as most enjoy the jobs they have now and the remaing choices are not as much fun.
While this isn't necessarily a bad thing, it is if you're one of the low level players looking for an experience party. I've found, it's actually easier to solo and if I can work it out, I can PL myself at a much faster pace than I can with a party to 37. Good parties earn more exp than solo and if they're really good, more than with a PL, but with players being so sparse, it's rarely the case. Try finding BST pets that spawn EM-T in your level range; they have very low HP and make for awesome exp if there are multiple in close proximity. That's mostly how I make my way to 37 (subjob level). Beyond that, I can only recommend the basic things which is make friends with people your level, find a static if at all possible, or find a friend or two to party with on a consistent basis.