Keep experimenting, keep trying to make more money. After a few months making more money will become more and more challenging since you will be running at full tilt with the basics, but keep trying. Every situation is different, but here are just a few things that I have seen work. A vendor in an area where there was no phone close by, bought a Cell Phone. This is rather obvious, but a vendor working a beach area started selling Tanning and Sun Screen products and tripled his bottom line.
Many vendors sell tourist related T-shirts at huge markups.