Save the boost for a Mesmer. Game play is so different after chrono that the lessons learned leveling may not even be valid From my understanding.
Necro is easy and a joy to level. I boosted a guardian and am leveling a Mesmer big mistake.
The posters above tips about run speed are valuable. I found dagger was my go to main hand weapon. I usually ended up with axe for ranged.
Once I got greatsword I fell in love with the class all over again. Feels so much more fluid than my guardian or the mesmer.
Ranger is even easier to level so do not waste the boost on that either.