I'm working on Farming on a level 3 skiller I have. My goal: 99 Farming while putting in the least amount of work and money into it; no Magic Seeds or pansy-ness involved.
That being said, I basically just plant my crops, and then play some COD4:MW2 or Vinesweeper while I wait for the to grow. While, yes, it takes a long time to get, and requires a lot of patience, but it is easily one of the easiest skill to 99. Not boring, not tedious. Really easy; it just takes a long time.
Been doing it for 3 days now, and I'm 55 Farming. I hope for 99 within around 3 months.