Okay, if it helps, I just did dirt for the first time last night. First note, do NOT start this project at 11pm if you have to be at work at 7am...and you plan to sleep. Of course, this is probably a "duh" moment for most people...but apparently I'm just not that bright, lol! :)
So, I watched some youtube videos, and the steps that ended up working fairly well for me:
Put down about an inch of dirt. Take out the large chunks and any wood peices, and smooth it out.
Dampen the dirt with a shower of water, not enough to splash or displace the dirt, just a gentle shower to get it started.
Put down a hefty layer of gravel, like at least an inch.
(other's have rec'd to me to put down a thin layer of sand at this point between dirt and gravel, I will definitely try this next time)
Using either a python or a tube and pond filter pump, slowly, SLOWLY allow the water to go into the tank. The goal is to avoid stirring anything up or moving the gravel around.
It's going to be cloudy. In the video, it was nice and clear...I was not that lucky. ;)
I filled the tank to about halfway full, put in my plants (which made it really cloudy, but there were several crypts so they needed fairly large holes in order to be sunk into the substrate which probably had quite a bit to do with it), and then drain.
I ended up having to half-fill, and then drain, three times before I got to clear water. The fourth time I filled the tank there was just the slightest bit of cloudiness in the first few minutes, but then that was good to go after filling the rest of the tank. :)
Overall, it wasn't too bad. I freaked out after the second water change because I was afraid I'd be changing water for hours, but after that third go-round it was good, so it wasn't too bad. :) Just plan to devote a few hours to doing it, have a movie on or something. :)
I used gravel because I tried sand once before and was very, very sorry. It would not ever clear up for me...but I know other people don't have any issues at all, particularly if they use the paper towel mothod (lay down paper towels as the tank fills to prevent cloudiness), so I'm just one person who had an issue. :)
I hope that helps!! :D