The best practise is to learn the specifics of the species you are caring for. Too many people put “Bonsai" under a single banner.
Each species has it's quirks and needs. For example, if you water a black pine too much the needles will start to turn yellow letting you know not to water as much. Where as here in Australia a lot of our natives can't get enough water. We keep them in trays of water so they can soak up what they need in between watering.
Learn these few things for each species
How much sun exposure?
How much water?
What soil is best?
When to fertilize and what to fertilize with.
How does the tree act in each season
These are just the basics but will keep your Bonsai Happy. Once you learn these basics for each of your species you can begin learning tactical pruning and wiring techniques.