When installing hardwood floor which room should I start with?

Below is the layout of my ground floor. I would like to redo the hardwood floor. The old one is still in place, the house was built in 58 and I believe that the floor was never replaced so it is about the time :-)

The grey areas do not need hard floor. I would like to start with the empty bedroom but I am not sure how that will impact the later work for the long central hallway and the living. I have never installed hard floor in my life and I read that you need to start with the biggest room, parallel with the longest continuous wall My reason for doing it this way is the lack of experience. Since that is the smallest room I can try to learn to install hard floor without wasting tons of money, time and without turning everything upside down around me. I want to be able to regroup and call a pro if I fail or get bored
The other question that I have is this: is it doable to install different hardwood floor in each room ? I would like to do that for variation and to give each room a specific personality or touch to say so...

Bigger picture here: http://i.stack.imgur.com/WF5eh.png

 

I think I'd snap a straight reference line down the hallway and then measure down from that reference line and start in the bottom left corner of your picture. This would allow you to work (up) toward the chalk line and down the hall. The flooring would continue through the doorway of the office and continue up to the top right corner of the house.

By using flush transitions at your bedroom doorways you could reverse the direction you lay the bedroom so that you could start laying on the other side of the transition at the bedroom doorways and work down to the bottom wall.

Since the layout in the hall affects the exact position of the flush transitions in your doorways, I wouldn't recommend starting in the bedrooms. If you don't position that transition exactly right in the doorway you will be kicking yourself later.

 

I was hoping that it would be possible to start with a smaller room.
Starting with the living would force me to go big when I am a beginner and that is risky

 

If you REALLY need to start in a bedroom, I would still snap the line... maybe along the bottom hallway wall in your drawing... it should be one line and go all the way through the house from left to right on your drawing, and through the doorways. Check the measurements from that line to each wall and try and center it if needed so that you don't end up with any tapers. If you can't snap a chalk line, use a mason's string stretched as tight as you can get it... placed around 2 nails or screws on each end of the house. Leave those nails/screws in place so that you can hook the line up again as needed.

Check your layout (where the increments of each board will end up by the time you get to another wall) so that you try to avoid any small rips against walls. Adjust your layout as needed. Start inside a bedroom, partially into a doorway and work in toward the bedroom and away from the doorway. It's CRITICAL that both bedrooms be lined up EXACTLY with your chalk line in the hallway and that the layout is perfectly parallel to that line. Use a spline to change directions at the doorway so that you can work in the opposite direction out into the hall. See photo illustration.

Work the hallway up... into the office and entrance, leaving the lower part of the living room undone. Then for the lower half of the living room, put a spline in the groove and work from your reference line down toward the bottom of your picture.

Where you start isn't as important as HOW you start it. The very first board you lay will pretty much determine everything about the entire floor- how straight -or crooked- everything else is going to be. That's why that string line (and thinking about all the layout) is so important.

 

I'm afraid it is one big project to begin with. The old hardwood should be removed and your subfloor beefed up with additional ply. The industry standard today is for minimum 3/4" underlayment. The best I think you will have is 1/2". I would add no less than additional 1/2" and probably 3/4" Advantech. One room at a time will drag out the construction beyond manageable time frames and keep you in a constant state of dis-repair. You will also end up measuring from different floor heights and still try to keep everything perfectly parallel to each other section to be installed. Monumental task to say the least. I see this as an "all in" or nothing situation and if you call in a contractor after the fact, you risk needing to start over if your measurements were incorrect or he can't rectify the situation to your liking.