I've built a couple computers myself as well... I had never soldered anything before doing this project, so I bought an AM/FM Radio Kit and practiced with that until I felt comfortable soldering. I think I did rather well considering... Other than the practice, I think the thing that helped the most was using very thin gauge solder (.40mm / .015"). Check out the soldering tutorials from EEVblog on youtube, they were also very helpful.
Going from a regular keyboard in qwerty layout to a qwerty layout on the ErgoDox has made the transition a little easier (as opposed to switching to a new layout completely), although the keycaps that I got don't have markings on them, so I have to rely on my memory of the different keys in relation to one another. I'm actually kind of surprised at how well my hands know the qwerty layout. I still make lots of mistakes, but so far I feel like I'm adjusting well and getting better each time I use the board. I'll better be able to judge once I get back up to regular typing speed.