J.H.
When I was paying my way to conventions as a youngester -- mostly field trips for journalism and such, I had a neighbor who wanted her windows cleaned, her silver cleaned, weeds pulled, ect... I also babysat, washed cars for the neighborhood, and offered myself as a mother's helper to the moms around. I also dusted, cleaned houses, anything that would make money -- then I gave 80% to the savings account and kept 20% to have immediate gratification of my hard work - which kept me working :)
Good luck!