It's actually very easy to level DPS classes solo. You can get from lv 1 to 50 in less than 30 hours by doing leves and FATEs (I haven't been on a single party doing FATEs since I started). I play every now and then and at least of 3-4 hours a day you can get the class fast.

This is what I do:
1-10: I walk killing what I can walking towards to the Teleport Crystal on Central Shroud and I set the Home point there. When i get there I'm about lv 4 with Food and the FC exp buff on. I just do 1 or 2 lv 1 leves to get to lv 5 and I always set them to high so I can be level 5 and fight vs lv 8-10 monsters.