There is an art to picking airplane seats. Make sure the size of your bag will fit in the overhead. Different sizes of planes hold different sizes of bags. I have been on planes where they take all but the smallest bags and check them at the gate. If there are things you want with you on the plane in the cabin make sure they are in your purse or small baggage item.
Have you ever sat in the seats next to the bath rooms? Not such good seats. People standing over you, bumping you and then there can be smells. I stay away from that area.
The bulkhead seats offer a little more leg room for those with long legs but you can’t put your bag under the seat in front of you. It will be in the bin overhead.
Aisle seats let you get out to the bathroom without having to ask people get out. Be careful of the people and carts going up and down the aisle. You can get bumped.
Window seats give you not only a view out the window you also get a place to rest your head to sleep.
The back row of seats generally do not recline so they can be uncomfortable. In some planes the seats get closer together the further back in the plane you get.
If you don’t like the seats you get when you check in go to the gate counter to see if they can change your seats. Try to pick your seating when you book them. You can do it online or view the seats available online and then call and have an agent assign them.