Nice job!

Thanks a lot! How long/how many attempts did it take you to get to a sellable quality?

No problem! I want to say at my 4th head I was able to sell it as a partial, but that doesn't mean it was sell-able quality! Some folks are just looking for something cheap and maybe that was it at the time. Ideally when you make stuff you should make it with the goal to improve, not to sell. I think that helps make a difference. Once you accept that sometimes you'll make mistakes and you have to go back or even start over you work better to improve your skill.
Find out what you need to work on the most and pace yourself from there. Ask for help, get redlines and critique, look at real animals (not other's fursuits) to help you get the shape of the species right. Years after I started selling fursuits, I came across the community http://fursuit.livejournal.com/ browsing their memories section it is full of tutorials how-tos guides and questions I may have had that others asked and got answers to. So I learned from there to also improve the quality of my suits.

That's potentially very helpful. I based mine mainly on a youtube tutorial but some of their instructions don't seem to fit what I was aiming for.

I find tutorials to be bare-bone guides. They give you the basics to make something, but you're required to fill in the gaps to make it into what you need to.