I'll shamelessly plug Najena - it's busy with lots of folks at all levels.
Here's some starting tips (or...What I Wish I Knew When I Started)
1. Get through the IoR, do the armor quests to outfit yourself.
2. Once you get to your hometown, find and do as many quests as you can. You'll find that you can get armor, weapons, food/drink, bags, and even furniture just by doing quests.
3. Don't worry about money, you will be poor for a while. But quests can make up for that.
4. Find the Broker in your town or one nearby (There's an outdoor one in Qeynos Harbor and North Qeynos). That's the NPC that sells things that other players are selling. You'll find most of your gear and spell upgrades here.
5. Speaking of spell upgrades, you'll start with Apprentice I (worst). You can buy Apprentice II at some spell merchants but they are a waste of money since they are not significant upgrades. You can craft your own upgrades, buy them from the broker, have a guildmate or friend make them for free, or find them on mob drops.
6. Don't be discouraged by the seemingly low amount of people around. Most have advanced beyond the beginner zones. You should still be able to find enough folks as you need.
7. Play a few classes to see what you like, then settle in on your special pick.
8. When you find your room, you will have 2 house vault slots. (right click door > Access > Vault) It's only 2 slots but you can put bags or boxes in there, expanding your storage space.
9. Speaking of bags. Get some. Buy some. Make some. You will need lots of carrying space in your adventures.
10. Have fun!