We just came back from Ireland and England and flew multiple times with Ryan Air. Here's some tips which may help you if you are flying with them.
You must print your boarding pass from home before getting to the airport. You can do this 15 days before departure.
They will charge you if you do not have it preprinted.
If you are not an EU citizen, you must get a Visa Check before going to security. Your boarding pass should say "VISA CHECK". There's a special desk at the check in where they verify your ticket and your passport, and stamp your preprinted boarding pass with Visa Check.
OH make sure you use the name that is printed on the passport. We saw one person who used her nickname instead of the name on the passport, and that was such a headache for her.
Ryan air allows you to carry on ONE item. THat means one bag OR one purse OR one suitcase (which must fit in their sample bin). They will stop you at the gate if you have a laptop bag and a pack. You have to be able to shove your pack into the bag or vice versa. One means one!
Also, make sure you have a zip lock bag for the liquids. Dublin does not give you free zip lock baggies... you can buy them at the vending machine for 1 euro.
And the only thing free on the plane is the in flight magazine. Buy ahead or bring money if you want tea, coffee, soda, crisps, candy, etc.