Hi there,
I myself will start the game not in a rush but as I allrdy made plans how to hit what level at what time and in what way I will probably stay focused to that. About Exping at all I will just rush the start to avoid the overflowed low level Areas as fast as possible and then I ll cruise around the diffrent regions doing events and stuff. Another good point is to always gather all you can find and dont forget to buy some gather tools at that point. The Way I play I can reach level 20 pretty fast but due to my lagging and disconecting problems at my current home (still the same at launch probably) I will do much of that alone or in small group. Later on with 20 I will start then grouping in WvW and doing some Skillpoint runs (means gather people from the guild and explore region by region to get the skillpoints there also reaching all the waypoints etc will be fun I guess). Reaching 20 is good in my opinion because its much more confortable after 20 with traits + skills (3 utility slots) and weapons (I figured out where to buy some green weapons for Karma-Points at level 20 within my exping route). Also a good point is at the start to do the instance solo quests they are worth a lot of experince and some armorparts ( I always choose the Vitality ones due to more health is more easy to exp in my opinion) tht can help to get rid of the starting zones. After all that I will when not doing the guild actions do some region exploring. Exploring Region by Region is a good way to Exp at all and it feels much lesser chaotic then rushing like crazy through it. Thats all for now from my side.
greeting jani