Answer:
1. The pay for hour must be double for a regular day
2. There must be some kind of work /time compensation if i had to work the next day. For example, get to work one hour later or something like that.
3. It's not economical, but must a job i like and enjoy.
The above considerations are only aplicable if the work is on every friday. If its just on special event, i think there wont be so much trouble.