Well we started out doing a one shot Thanksgiving themed campaign that I found online but I didn't take the time I needed to look it over and put my own thoughts into it than we decided to go with a campaign that I've been working on doing myself where I had the time and the thought into almost every detail of how the players could do things. My wife is one of the party members and with that being said even with it being my first session she thought I did pretty well. The other members of the party also had fun with what we did but there were times that I was flying by the seat of my pants so to speak and still looking things up in my books and online for reference and trying my best to give them the best experience that I could. I am going to go through the books tonight and try to get a bit more organized because the party members want to continue with the campaign on Saturday, so I'm going to continue to try and get better by being a bit more prepared for the curves that my wife has been known to throw at me since last night.
This sounds like you did quite well, considering it was your first time. You recognized that you weren’t sufficiently prepared for the game you had set out to run, admitted to that, and pivoted to an adventure you were better prepared for, which was a very smart move, and the players enjoyed it enough that they want to continue. That’s a great place to be in.
You will probably always be flying by the seat of your pants. No matter how much preparation you do, the players will always end up doing something unexpected. That doesn’t mean you shouldn’t prepare, but it does mean that you should go in expecting to need to improvise at some point. I would recommend not putting too much stock in advice about how much or how little to prepare. That’s a very personal thing, and you will always be a better judge of how much prep you need than any of us here will be. Just keep in mind that it will always be necessary to go off-book when something unexpected inevitably happens.
I would also recommend breaking yourself if the habit of looking things up at the table. Flip through your notes if you need to, sure, but “looking things up in my books or online” can be pretty harmful to the pacing and flow of play. In my opinion, it is better to make an immediate call that might turn out be “wrong” than to interrupt play for a minute to find the exact rule.
Also, try to keep in mind that you will always be your own biggest critic. You may have felt like you were flying by the seat of your pants, but the players probably didn’t notice. You’ll be much more intensely aware of your own mistakes than they will, and at the end of the day, if they had a good time, you’ve done your job as a DM. Don’t let that be an excuse not to keep striving to improve, but do try to let it relieve some of the pressure to be perfect.