Air travel sure isn’t what is used to be (in many ways), which makes today’s minimal amenities and uncomfortable seating all the harder on those of us who remember better times. It’s simply not fun to fly commercially, and if you feel otherwise you probably haven’t flown much. The allure of flying is a temporary illness, cured by taking a sufficient number of flights. While you may be excited about the destination you’re heading toward, the flight itself and the airport processing are nothing to get excited about: it’s merely something you have to endure.
If you decide you've made a mistake and your have too much carry-on baggage, ask the gate agent if you can gate check some of your bags. They'll tag your bag and take it from you on the jetway as you are about to board; on the other end, it may be picked up in the some way or sometimes it goes to baggage claim. There's no fee for gate checking. If you find out you're on a tiny plane definitely consider it. It's not wise to gate check anything valuable or vulnerable like a laptop.
I've found traveling light makes a big difference in ease of flying. I used to carry a monster of a laptop in a large case with everything I might need, and it weighed a ton. It was also causing me a lot of shoulder and neck pain because it was an over-the-shoulder strap bag. Not these days: I go for thin, small, and light every time and my bags are always wheeled. Personally, I like the rolling laptop cases from Kensington and the Samsonite Spinner suitcase (which can pivot in any direction). Think carefully about the size you get and whether you'll be using it primarily as a carry-on or not. If you're going on a long enough trip where you need a garment bag, I recommend the simple but study and reliable Wally Bag.
The TSA will screen you and your baggage. They are not the joking types, and using words like “bomb” or “weapon” out loud is extremely unwise. Indeed, it’s best not to say anything at all unless spoken to. Policies change over time, but at the time of this writing computers (but not tablets or phones) and a few other classes of equipment need to go in separate bins; the rest of your electronics can usually stay in your carry-on bag. For your carry-on baggage, liquids are frowned upon except in extremely small quantities and are to be put in a bin in a plastic bag. You’ll have to remove shoes, belts, and coats/jackets and put them in bins; you’ll see experienced travelers undressing while they’re in the security line and move through the whole process very efficiently.
Lots of people like to use their electronics. Increasingly, airports are making arrays of outlets and even work areas available for this purpose. If that’s not the case at your airport, there is an art to hunting down available outlets. There have to be occasional outlets for things like custodial vacuuming, so skilled travelers get good at seeking them out when they survey an airport waiting area. if you've ever seen a traveler slowly canvassing the waiting area, eyes downcast toward floors and pillars, they're probably on the hunt for an outlet.
Flying may give you time to do things you often can't find enough time for normally, such as reading or doing some serious thinking. Though many travelers don't utter a word to the person sitting next to them, if you're the talkative type you may find striking up a conversation with your neighbor to be a good way to pass the time.