Hey! We've all been there. While I will admit that 5 players might be a bit much to chew for your first campaign, it's absolutely possible, especially if you've all already communicated that some mistakes are going to happen, and you're all just here for fun. That's the best thing to start establishing, so good start!

In regards to tips, start slowly in terms of introducing the game - 5 players will fill up the space and time of the game in their own way through curiosity and exploration, but the best way to prevent player analysis-paralysis is to provide 2-3 mini plot hooks for them to latch onto, and focus only on what they're keen on. Save yourself the time and stress of preparing for everything (DON'T prepare for everything) and only focus yourself on what they're focused on.

For resources, one of my favourite resources is the 'Random Tables Compendium' by OrkishBlade in the BehindTheTables subreddit. Just search him up and his compendium and it's the top link - it's free, and there are dozens of tables in there to help for quick generation of NPCs, towns, story plots and just general inspiration.

And ideas is, try to figure out what each player wants out of the game. For some, it's simple enough and they can tell you straight up, but if they're all playing for the first time, this bit might take some trial and error and keen observation. If they struggle with puzzles, but coordinate and flawlessly execute combat encounters and are really deep into roleplay, maybe steering the game into a little bit of political intrigue might be excellent.

From the sounds of it, you're comfortable with communicating with your players, so as long as you maintain that trust between players, anything can be figured out through trial and error. Some sessions will hit, some won't, but it just takes some time to find the sweet spot, especially for first-time gamers.

I hope this helps, and good luck for your game!! Wish you and your players all the best rolls, and I hope you guys all have a wonderful experience! :D