If you are flying with Ryanair be sure to check-in online at home. Bring print-out or your phone to airport. If printing, ensure your printer is set to highest quality setting to be certain that the scanners at the airport can read the barcode. Make sure your phone is fully charged.
Having checked in online, you will need to go to bag drop for checked-in luggage. You will need your boarding pass for this and your passport.
Then join queue for security. You can usually check the likely waiting time for security on the airport's website. Things are improving significantly since the madness of June/July queues. You will need your boarding pass here.
Both airports/airlines that I used this week had the normal post 9/11 security procedures in place.
Liquids to be placed in 1 litre zip-lock bags, they were available at the airport. Normal individual limits apply. Best to place toiletries in your checked-in baggage.
You can't take drinks through security but you can buy them at the other side.
You will need to remove portable electronic devices from your hand luggage and place them alongside the bag to be scanned. Do a little number count - bag, phone, jacket, belt - 1,2,3,4 to ensure you retrieve the correct number of items at the other side.
Make sure there are no coins or keys in your pockets. You will have to remove jacket and possibly boots/shoes and walk through a scanner.
Even if you don't trigger alarm walking through security you may be selected for a random pat-down.
Take note of the departure gate number and allow yourself plenty of time to get there - ours was 2 minutes on the way out but 12 minutes on the way back.
Have a look in duty free. Be mindful that the airline may be fussy about extra bags in addition to your allowed hand luggage. Check whether you can leave your purchases at the airport and collect them on the way home.
Your seat will be allocated on your boarding pass, so there is no need to jump to your feet and queue for the boarding gate once it opens, sit and relax, just keep the queue in view.
You will need to show your boarding pass and passport at the departure gate.
Be mindful that the cabin crew may want to take your large cabin bag from you at the top of the steps for putting into the hold for the flight. For most people, that won't be a problem but be sure you are holding onto any medication or passport in your small handbag.
There's rarely any free food or drink on board, maybe on charter flights. Expect to pay through the nose. Duty free is available on board.
Hope this helps!