I use an old Targus notebook bag something like this:
1 central cavity and 1 big velcro pouch on the front.
I keep my DX6i in its original foam container in the central cavity and a field kit in the front velcro pouch. The field kit is in three parts:
1. Small, clear zip bag for CA glue, tape, toothpicks, etc.
2. Small, clear zip bag for small tools; screwdriver with multiple tips, needle nose pliers, scissors, etc.
3. Lipo battery "caddy"
This caddy is a separate little bag that holds my 1S batteries for Ultra Micro planes plus a 2S 750 mah, 3S 1000 mah and 3S 1300 mah for my Stryker and Easy Star planes. It means I can leave the transmitter and tools in the car but take the Lipos into work with me on a hot summer day without worrying the Lipos will get too hot in my car.
Using this shoulder bag means I can carry my field kit and still have both hands free to carry two planes out to the flying field.
I also keep misc pieces like spare props, battery checker, etc. in the many little pouches and pockets that you find in such a computer tote bag.
I keep my planes in the trunk of my VW Golf and the field kit case in the car so the heavier bag won't shift around and hurt the planes.