Though ADR is unavoidable sometimes, it can be time consuming, expensive, and frustrating as hell. That's why it's imperative to know how to record good location audio so you get it right the first time.
If you need a few tips on how to do this, Sound Designer/Sound Mixer Jonah Guelzo and Boom Operator Tyler Lyons walk you through their own recording process for their feature film Where are you Bobby Browning?. This video is great, because you'll learn a wide range of basic and advanced techniques, like how to attach a lav mic to someone's chest, how to hide mics inside a car, and what kind of professional gear to use if you want to do dual system.
Check it out below:
Probably the most important lesson to learn from this video is this: don't have a "fix it in post" mentality. (Sound is supposed to be recorded not fixed, guys.) Even though editing software has become so incredibly powerful, it's still seems to be no match for the wacky things we can do to make our audio just terrible. Being meticulous and intentional about getting the best recording the first time around will make your (or your editor's) life during post so much easier (and cheaper).