1-20 very easily (requires 1-3pp)
the quickest way i have come across to do this is the collection qsts, as soon as i went thru the blah blah blah from the startting npc, i went right to freeport in my case. when i got there i went to east freeport , there is a collector pretty close to the broker on the docks (left of him around the building). in qeynos go to north qeynos there is a collector close by a broker as well. i dont remember exactly how many collection qsts i have completed for this particular char , rough guess would be 25 or so , 80% of them lvl 45 +. but i went to 20 in about 45-60 mins i spent just under 3pp which isnt much for the time saved. i know pretty obvious but just wanted to point it out in case someone overlooked it. of course by server you may spend more or less based on supply and demand .