Many of us, have read GM-sections in RPG, RPG blogs, forum discussions, and sometimes books about the storytelling art.
All of these contains tons of interesting tips/techniques (and some will contradict each other, you don’t GM a gritty mega-dungeon and high-school drama game the same way), so I am curious which ones are your favourite and how do you use them in your game
If you need to “cheat” (e.g. fudging a roll because you made your monster way too powerful) then never tell the players, it will only ruin their sense of immersion.
Try to do voices, players love them even if they’re shit and it helps distinguish the NPCs. The voices don’t have to be remotely good and you don’t need to be good at accents, just try things like “gruff voice” for the grizzled mercenary or “weirdly enthusiastic” for the mad old wizard.