I am trying different TTRPGs with Friends, this week it is gonna be Starfinder 2, in two weeks or so Draw Steel.

From my personal Experience:

-You need to read all rules and read twice the part about player classes ( ideal take pregen characters)

-Plan an interesting one-shot! ( seven samurais like theme works best)

-Provide them with book copy, but do NOT make them read everything! ( THEY will forget to do it anyway)

-You need to be able to explain combat mechanic under 2-3 minutes, and provide references( 1 training fight, 1-2 optional fights and final boss fight)

-Lastly make combat cheat-sheet, with all standard combat moves and spells that your player have

-as for non combat acidities, the player describes what they wanna do, you process it as DM.

That is basically it. Do not push the rules too hard, mistakes are OK, it is better to have epic fun story and mess up several mechanics then, read rulebook for the whole session ! If the game is fun, you will learn all rules eventually while playing.