But the fastest way is to bring him gifts u find in Dark Soil which can be found all over the Valley. His favorite is "Blue Feather", which will give u cca 1000 rep with him; all other stuff like "Ruby Shard" or "Jade Cat" will do as well, but give only 500 rep. It is a grind, but if u focus really on one character from all those Tiller guys, u should be able to make in a day.
Anyway, if u want some more extensive reading, check this link on wowhead: http://www.wowhead.com/faction=1276#comments
You can read up some more about him by yourself in case I missed anything or don't understand something I said.. or you can just reply here!
Edit: Ricardus has stolen my thunder of being helpful! :(
edit: Gosh darn it beaten to it and been done in better detail...
hand them ALL in to hillpaw, some he likes better than others (blue feather gives 990 rep, others give 550 ish iirc)
these dark soils respawn every 30 mins approx, so you can farm quite a lot in one day.
to begin with, just fly slowly around looking for them, once youve done a lap or two you will be able to spot them a mile off.
(if you want, use an addon like gathermate to remember the spots where ones were famred before)
i farmed these and got every single tiller to exalted without really resorting to dailies.
alternate place to farm is around the temple of white tiger in kunlai, but theres not anywhere near as many as heartland