This question was asked 487,502 times on the last weekend test. To be fair, it is a little confusing so unless things have changed in the last two weeks , let me spare a few of you this dilemma.
After you leave your starter planet, the shuttle takes you to some sort of orbital station. After you arrive in the hangar, look for an elevator that takes you to the main level. As soon as you reach the main level, there will be an NPC near the elevator that gives you a ridiculously simple quest to go and talk to your class trainer on that orbital station. Simply talking to the trainer completes the quest and allows you to choose your advanced class.
Make sure you are at least level 10 before you leave your starter planet or you will not be able to choose an advanced class.
Beta testers: my testing experience is limited to the last weekend test so feel free to correct me.
Comments
You can select an advanced class on your faction's capital world as well. there will usually be a quest NPC near your trainer or Master / Handler.
You need to be lvl 10 to select an AC, but you don't have to wait until you are lvl 10 to leave the starting planet. In fact, I usually leave at lvl 9, and let the exploration XP boost me to 10 when I get to the capitol.
I did all the quests on starter world but once u get to fleet the map shows u where your class trainer is and where the crafting trainers are. they arent hard to find and then all u do is go to trainer at 10 they tell uc an pick an ac and voila its done
i didnt really pay much attention to my smuggler one as i was only testing starter worlds and some clases to see wht they were like in my gfs beta but it ws pretty simple to train.
From what i saw of your post though it was pretty much spot on. I think more people in beta shoudl of read up i knew going in i had to be a 10 to train an ac thanks to reading up on game on tor site and previews.
I've always hit lvl 10 by the time I leave the planet. It is really convenient to do so as once you get to the space station you have a quest giver that leads you right to the quest giver that introduces you to your AC choices as well as crafting and various other skills. So it just flows better in my opinion and you are better skilled if you hit up the flashpoint that takes you to your capital planet. Although now that they nerfed that flashpoint maybe it doesn't matter anymore.
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Ethion