I'm loving the DIY musician thing too. There's nothing like artistic freedom (within the limits of commercial requirements, that is

). It's very demanding to learn the ropes of all aspects in the process, though, so collaborations can be a good idea.
Besides the standard talking into each other in the start, it's also a very good thing to have the record straight about your goals and your focus. But also, I think it's important to be clear about WHY you want to engage in collaborations. If you are clear about your gains, it's easier to give other things up, and a collaboration IS a give and take. Being too strategic about it doesn't work, you have to have a positive motivation, in my experience, and not just do it because you see that's what other writers do. Otherwise you'll be holding things back and can't communicate sufficiently to get the job done.
In fact, the ability to write on your own, is above the ability to cowrite, in the publishers list over qualities they look for in an writer (see Ralph Murphys list
http://www.ascap.com/nashville/murphy/murphy2.html). When you consider cowriting from a business point of view, as a new writer, you'll actually need to prove that you can write on your own, and then when you can bring craft and fresh ideas to the table. From a business point of view co-writing is mostly done because it increases the shopping odds when you have two publishers involved, or is done directly with new upcoming artists, before they are released on a major label, and thereafter are unavailable for outside writers.
The worst thing about cowriting is that you inevitably give up some of your artistic freedom. It's compromize or the highway!

You just can't do what you want, you have to communicate the things that are self-evident in your own mind, but needs to be agreed upon when a cowriter is involved. If you are working with lyricists, they are often very specialized, and doesn't understand the other aspects of finishing a song from a musicians point of view, so that requires a LOT of communication. DIY'ers work with lyrics, composing, get coaching on the raw song, arranging, recording, mixing and marketing.
The thing about collaborations is that all of these processes needs constant attention and (re)evaluation throughout the production process. This requires a lot of communication as well as expertise, which often is in favour of the DIY'er because of the research and training involved to get there. And it slows things down. It's a great puzzle, and the workload are often very uneven, so it's often better to collaborate with another DIY musician, so you not only share the evaluations but also the actual producing, and the workload.
I've done a bit of long distance cowriting, primarily email exchanges and Skype sessions, and if you're anything like me, I hate writing things that's more easily said face-to-face, so Skype sessions are really the way to go, unless you like to be in endless mail exchanges that leads to nothing but trouble. Face-to-face sessions even better, if you at all can.
After trying the long distance cowriting for a while, I'm inclined to less co-writing now. I'll work on the craft and my own portfolio, and try to get some stuff through with publishers/libraries, before engaging in more cowriting. Not to say, it won't happen, it's just not that high on my priorities list as it used to be.
On the positive list, co-writing can really improve your work, you can make great new friends, you can get contacts you'd never dreamed you would get, and it can help you come out of a rut and motivate you to learn new stuff.
Just some of my thoughts about it.