Pick out the skills you like the look of for the time being. There are quests throughout the game which give skills as a reward which will save you having to spend gold at trainers. The cost of buying skills really adds up so check wiki to see if you can acquire the skills you like from quests and you'll thank yourself later.
http://gw.gamewikis.org/wiki/Main_Page
Edit: The length of time it would take to get all the skills for your profession is up to you. If you unlock the skills by playing PvP and spending Balthazar Faction you can then buy those skills at any Skill Trainer in Prophecies (excluding Elites). You can always buy a Prophecies unlock pack from the online store and you'll be able to buy all non-elite skills for your character from any skill trainer providing you have enough gold. Whenever you buy a skill, the price goes up and caps at 1,000g. 1k per skill is pricey.