Zone chat is the common tool, then entering new zones I always help anybody as port to player unlocks wayskrines. Helping people usually get them to help you too.
Else I do everything in guild, note that most ask in other guilds including trade guilds before asking in zone.

Took a couple of weeks but I am in a PvE guild (not trade guild) and kept asking around each night for people interested in forming a leveling group. I ended up finding 3 other people who weren't afraid to use TS and wanted to roll new alts for the group.

We each created a different class and now play our alts 3 nights a week for 2 hours each and are leveling them up together. It really does bring a breath of fresh air into the game grouping (and dungeons are a breeze).

(1) Find a PvE guild as trade guilds are mostly filled with people that only solo.
(2) Be willing to use voice comms. It builds friendships more than a chat box ever will and helps ensure longevity within the group.
(3) Be ready to start from scratch. Its a great alternative to playing your main.

Good Luck in your search.

I am in 4 trade guilds and 1 regular guild. The most active ones are the 4 trade guilds. The banter between members, new and old, are funny and often makes me LOL. They are always very helpful with dungeons etc as well as questions about the game. Friendly and hilarious bunch. The least active one I have is the regular guild which I am going to quit today and join another trade guild. So from my experience (short as it is), its not so much the type of guilds that makes the difference but the members in them.

Yes, the trade guilds members go out PVP-ing, PVE-ing, dungeon-ing etc together often, from what I can see on chat when they invites new and regulars to join them.