My first advice to people coming back, is find your old account. Old characters are not worth much because you can make so much better now and it is a lot easier, but an old account will have a lot of benefits. Also I recommend making a new character and playing it through some levels. At some point you may feel confident and will want to skip ahead to a higher level character, but when you come back it is better to start from scratch. A lot of people suggest the tutorial which I guess is worth it for new people, but personally I prefer just making a new character, going to one of my favorite old zones, and start killing skellies and stuff.
Also the first thing I do is spend 30 minutes to an hour changing all the game's settings. You need to setup your resolution to match your screen, then change all the settings to suit your PC, ie, max everything to look pretty. Then you need to rearrange all the UI which as default is all over the place. Move each component to where you want it and then right click them and select lock. And lastly, go through all the keys and change the main ones to be how you want to play. For me that is WASD and then common things like hail, autoattack, and con, all on nearby keys. I also put crouch and autorun nearby too. I then change target nearest NPC to TAB, and cycle NPCs to Tilde key (the squiggle next to the 1 key). Once you do all that, log out! That will save the settings so you don't have to do this again.
Then get back in, and go kill some wasps n shit and get some spell money.
p.s. If you find your old account, you get a bunch of uber AA abilities you can use to make life a lot easier, and also you get some free money and some other things like global chat.