Launching spacecraft from the lunar surface to Mars doesn't make any sense unless we somehow had the facilities to build the spacecraft there - something we couldn't do until we created a massive infrastructure on the moon. It'll be a long, long time before we're able to build spacecraft on the moon or Mars. We'd need facilities to produce aerospace quality alloys, electronics, and whole spacecraft assemblies. Until then, the critical components will still have to be built here on Earth. You can assemble large spacecraft in Earth orbit from components launched from our surface (e.g. ISS, Mir), and then fuel the vehicle to send it whereever you want to go. It simply wouldn't make any sense to build the components here on Earth, launch them to the moon, land them there, assemble them into a spacecraft, only to launch it on to Mars or whereever. The energy used to reach escape velocity to fly to the moon only to then land it on the lunar surface is more than needed to launch it straight to Mars.

I do support the reconnaissance efforts, both orbiting and rovers, to see if there are harvestable resources on the moon. If so, then perhaps it would be possible to harvest these resources and send them to Earth orbit for use there. For example, propellants produced from lunar resources could be used not only for Mars-bound spacecraft but for things like space tugs to do all sorts of things (e.g. boost deep space payloads, retrieve/repair geosynch satellites, launch space probes, etc). The key to making this worthwhile would be to find materials that can be easily harvested (if they exist), then build a reusable vehicle that can fly between the moon and Earth orbit. There are some novel ideas out there that might make this possible.