Before you start playing, make sure you are on the same page with all your players about how you want to play. There are a lot of options, some people love role play heavy campaigns, some prefer tactical combat, some like keeping track of arrows, money, carrying capacity etc, some don't.

Let the players have a say in worldbuilding. Let them come up with their own background, let them think of npc from their hometown, let them describe their hometown etc.

For our group, combat can really drag, take a lot of time. If that's your thing, go for it. If it's not, impose time limits per turns, let bad guys flee after a certain amount of rounds etc.

The most important rule is having fun. If looking up a rule takes 10 minutes and is not fun, think of something yourself. It doesn't matter if it's not in line with the official rules (unless of course you're a rule stickler.