Arguably the most important part of your equipment list, microphones, headphones, speakers, etc. are some of the pieces you will need when producing your own videos. This top-level introduction to audio will help you understand what audio solution might be right for you.
Two things you will need to understand:
Pickup patterns: these patterns refer to how and where a microphone best picks up sound in relation to the sound source-there are specific uses for each pattern where they work best and knowing this can help you select the right microphone solution for your needs.
Types of Microphones: the type of microphone does not necessarily dictate the pickup pattern-many microphones on the market have interchangeable "heads" that allow you to change the pickup pattern, so understanding the differences between a lavalier/lapel, large diaphragm, shotgun, bi-directional, etc. can help you save money by ensuring you get what's right for you!