What I do when I wax is I turn the iron on really low and then touch the wax against it quickly. I then rub the block right onto the base. I can normally cover about 5 inches for each stroke, then touch it on the iron again. It leaves a thin layer of wax on there. It looks like a thin layer of paste over the base. Once I have got good coverage on the board I then just iron as normal.
By waxing this way I use a lot less wax, which means that i don't get excess everywhere, like over the edges. Its also more economical. Which i really like because I like to use fluorinated wax.
Another advantage is that because the wax is thinly spread it heats up faster and so I can iron at a lower temperature and don't need to hold the heat on there for too long. I dont have to use those extra seconds to melt the droplets before it spreads over the board.This helps avoid damaging the base.
It makes scrapping a lot easier as well because there is less to remove.
The only downside I find to this method is that it takes longer to apply it. But overall I find it to be faster.
If you do still end up getting wax on there use a citrus based cleaner, which you can find at most snowboarding outlets.