I’m still figuring out what sort of build I want to play at the moment. Dual flame totems is pretty popular right now. In the past I’ve enjoyed cyclone builds, as well as playing a crit ice shot. It’s up to you really if you want to experiment a bit (which can be really fun), but I would recommend at least making one that you know’s already viable. The lists in the forums are pretty good for finding ones/referencing them:
Duelist
Marauder
Ranger
Scion
Shadow
Templar
Witch
As you probably know by now, the builds are built around the skills and the classes just provide ideal starting positions on the tree for getting nodes. To have a viable build that can survive late game you have to focus on having health (or/and Energy Shield). As well as your evasion/armour and resistances - which you’ll get a lot from gear.
After quests and getting quest rewards, the vendor in towns (that sells flasks and jewellery) also sells SkillGems. There’s a list of them here.
pathofexile.gamepedia.com is your friend, and will provide loads of information on skills, quests, anything really.
Ziggy D’s Quick Start Guide is a really good place to get going too: Playlist here
As well as r/pathofexile’s new player guide: https://www.reddit.com/r/pathofexile/comments/1zn0lt/new_players_welcome_to_rpathofexile_please_see/
Then if you have any other questions hit me up on teamspeak or something, and there’s usually a few other people who can offer helpful info.
Add me in-game, name is Figurine
