This series is how I'd rule on common situations or situations that have came up in my games.

Disclaimer: I'm just some guy, I don't have any association with the designer's of Dungeons and Dragons. I play Dungeons and Dragons (and other TTRPGs) for fun and if something more comes from it -- great.

That said, I try to objectively look at what the rules say (rules-as-written, RAW) and what the rules mean (rules-as-intended, RAI). Sometimes, I'll even toss in my own opinion/ruling when it differs from RAW or RAI and explain why I'm going against what the say or seem to imply.

When I make rulings, I try to consider what happens if I use the same ruling against the player. This means, if a monster had access to the same spells/features/situation -- would this ruling have a positive impact (or at least not a net-negative impact) on the game? If a player would feel the ruling would be unfair when it's used against them then they shouldn't be able to use the ruling against an NPC or enemy. Keep in mind that there is a difference between "unfair" and "good or powerful."

As a DM, it's important to pay attention to the details (you might be a little rules lawyery). Don't let it get in the way of your game but your guard should be up when players push limits -- understand your player's intent and be careful of angle shooting. Remember if something sounds too good to be true, it probably is.