Regarding parties, make sure you have your looking for party flag (located in main menu -> search -> your settings -> online status) up at all times. This is a relatively new feature that is often either taken for granted or forgotten about but a lot of the better party leaders use the search function a lot. Plus, it doesn't get in the way of soloing or doing quests/leves when you might otherwise be stuck sitting in a corner of uldah shouting yourself hoarse for 3 hours trying to get a party the more traditional way ;P

I also strongly recommend being in a good, friendly LS. A lot of players these days are all 50s but a lot aren't. Chatting about wanting a low level party might encourage others to level their lower levels with you, or at least they'll be able to share a lot of advice. It's very common for LS'es to provide free services, like making your equipment for you if you bring them the required materials or if you donate any farmed mats that they can use for others.