Start by making a list of what you would like the room to include: size, windows, flooring etc. Then find a trusted architect to do the plans.

I have always dreamed of renovating an older commercial building into living space. However, Klein Kitchen is correct.......the first thing that you must do is check with the city to see if they will allow you to use the space as a residence. If it is zoned exclusively for commercial use, then you would not be allowed to renovate it into a house. Hopefully the neighborhood is zoned for both uses.......... Keep us posted on what you do with this project because I am sure that there are some excellent ideas that we all can share with you once you have made the commitment to go ahead...............

Thanks for the replies! My wife suggested we talk to a local real estate agent, so i think that is a good idea... just that Im not sure how helpful they are likely to be if we arent selling yet :) As for saving for our dream house, I dont disagree, however if doing this up nicely over the next ~5 years or so while we live here nets us some extra in the eventual sale, then that of course will help us as well. Interesting thing happened today actually. I got a knock on the door and one of the older neighbours asked if he could take some lemons from the tree. I of course said yes. Anyway he was telling me he had lived in the street for 40 years. I asked him if the house had always looked like this, and he said no that ~30 years ago the old old owner did a massive renovation and pulled off the timber and put up the bricks and gutted the inside of the house. Interesting stuff!

Personally I would save the room you want done the most until last - often during renovations, whether you're doing it yourself or paying someone, you still get sick of the mess, having other people in your home every day etc and what happens is you finish one room and want a break which can lead on to eith takgin months or not getting the last rooms done at all. If the last room is the one most important to you, you will continue on until that one is completed and this gives a much better feeling of satisfaction than doing that room first because you have that build up of anticipation.