Hi Ben,
Further to what Rod has said below, here are some other pointers which I've found REALLY useful for me. I'm very new to BOnsai as well (7-8 months) so I completely understand where you're at.
- As Rod said, get a really good free draining soil - I use a 50/50 mix of pre made bonsai soil and diatomite. With such a free draining soil i've found it practically impossible to overwater my plants.
- Know your trees. For example Junipers like to be a little on the dry side and like a wet-dry cycle. Whereas a tree like a swamp cypress (which live in muddy water) can be practically kept soaked constantly. Once you understand each tree's requirements, you can regulate it's watering accordingly. I have a fig, but not the same variety as yours and I've found it to be fairly tolerant of my watering habbits, which in the beginning, were all over the place!
- Do the finger test at Rod suggested, but I go a little deeper in the soil, as sometimes the surface can be dry but beneath still quite moist.
- Watch the weather - The hoter and dryer the temp, the more you'll need to water, however still conduct the "scratch test". The same rule applies as the seasons change - winter vs summer.
- How much folliage is on your trees - If you've recently done a HARD prune or defoliated your trees, they won't be sucking up as much water as there were previously, as with no solar panels, they can't photosynthesise. So again, less folliage = less water.
I hope that's helpful. I'm also happy to be corrected if anyone feels i've given inaccurate info