@GatlingGull I have been playing for only about 4 months, but put in a lot of hours. I love pvp, so if it's pvp you want to do, I have learned that if you are going to be a caster, you have to ensure you have plenty of Crowed control abilities, as the game has plenty of them available to everyone and if you get caught in a chain, you probably will die before you can get a cast off, so CC is a priority, again that is for pvp.
No, you can't just go with some casual build. I suggest going with a build of the style you like to play, one from the Architect build that is a player favorite and as you gain experience, adjust it as you go.
Here is another very, very important point. Use your talent points very wisely, making sure you are getting the maximum you can from them, that is going to determine how good you build will be.
Last but not least keep upgrading your gear and get them enchanted with both regular ones and REs. Make lots of gold as some of the better gear can be found in the Auction House compared to Honor gear.