We can figure three ways to level lumberjack, 1) chop and destroy, 2) chop and craft, 3) chop and bank. 1) being the "fastest" way, but also wasting loads of good wood which can be sold, 2) pretty efficient way and probably the best if you want to level faster than using 3) in which you bank your wood to be used in other professions or to be sold. In the beginning we would suggesting making smithmagic potions from the wood you chop, but it does get very unefficient and wood costly in the later levels.
We would suggest a combination of 2) and 3) depending what your intentions are, at this point we would like to remind this profession may take months to level to 100 depending how much you play in Dofus. For us it took 2-3 weeks from 1-60 and about a month from 60-100 so in total 6-7 weeks and we chopped 7-15 hours a day non-stop, competition makes this profession hard, as well as slow respawn times compared to farmer.