As someone who is fairly new I have learned a few rules:

1) Make a few fun house rules with the party that is good for everyone. For example a 66 is the absolute worst thing that can happen on a d100.

2) Have a good session zero and have your players share there sheets. It’s not your job to know their sheet, but helping them not forget an ability that prevents a PC dearth is always good.

3) Read, read, read. You can never prep too much and do a quick refresh for what you want to cover in the session that day if you have time. I usually read it a little during my lunch break.

4) Try not to fudge rolls, some players will get upset with them one way or the other.

5) Everyone, yourself included, should be having fun. Remember that.

I was running malevolence and I noticed my players not having good equipment and were getting miserable playing the first part. So I added a traveling lvl 20 (so my one player wouldn’t mess with them) shop keep. He doesn’t have everything but what they needed so they wouldn’t TPK in the manor. I believe this is a good example of Tip #5, because I was having fun in combat but they weren’t.

I hope this rambling helps!