If you're having it delivered to your location, have your site clear and then clear it some more: no joke, the guy who delivered mine banged into my fence as well as my neighbor's before bumping a rafter of the house!
If you're smart, congratulations: you've already got a slab or some easy foundation set up and can just have your new building dropped off perfectly. If you're like me, you haven't planned enough and will want to quickly scrounge some thick round material (think telephone poles) to set the container on for easier future adjustments. I used ~6" diameter round wood poles.
If you're going to fully move this trailer yourself or want to keep it portable, you're going to be entering the world of flatbed trailers. 16' utility flatbeds might be a feasible option for 20-footers, and they appear to be widely available on craigslist for ~$1,200. There are also DIY kits for the more brave and old car parts for the truly hardcore.
Winches, come-alongs and any other mechanical helpers will be your best friends during this process and later adjustments. Ideally, anchor to something much stronger than this tree stump and use the strongest electric winch you can get your hands on.