In what order and how to do the corners?

[Coca Carola]

Hello!
I'm going to build a smaller house about 28 sqm and have completed the load-bearing beam and the joists are in place.
Now it's time for the tricky part, which is to figure out exactly how each step is done and to make a drawing.
I will probably come back with more questions, but right now I'm wondering how to handle the corners?
I'm going to make a sill that is 145x45 and I'm wondering how to start the actual wall construction. One short side has no windows, is it best to start with that one then?
This is out in the countryside and there is no flat surface to work on, so the wall probably has to be built on site instead of prefabricated, but I'm having a bit of trouble figuring out how to deal with the corners.:blushing:
The next thing I'm wondering is whether you should buy the door and windows at the same time as you build the walls or is it enough to take the measurements and install them later?
Grateful for answers

Sincerely //Jonas

 

[andersmc]

Bold to start building first, and then make a blueprint!
Put in the floor joists first, and you'll have a surface to build on. Look at my friggebods build for some tips: http://malcolmsson.se/friggebod/

 

[Coca Carola]

Thanks for the tip, nice frigga!