Hi,
I am flying economy from Boston -> Madrid->Boston. I refrained from booking a connecting flight and will take a train to Seville and from Barcelona instead of flying after too-exciting experience with a connecting flight a couple of years ago*
I am anxious about keeping my carryon with me, and so I want to minimize my chances of having to check in my bag due to filled overhead compartments. I am not a frquent flyer, but experienced in travelling to Europe but I am bringing a friend who has not been, and I want to do everything I can to make a smooth journey on a budget!
I will pay for seat selection, and priority boarding.
I saw somewhere that Iberia was boarding from back to front. Has anyone flown recently and can confirm this?
Any seat selection tips, or anything else I can do to maximize being able to keep my luggage with me?

Thank you
(on another airline a couple of years ago-- work strike in Amsterdam. I had booked my ticket Bos->BCN direct with KLM and the system set me up with only a 45 min layover. Now i have found out this is impossible in that massive airport! First they auto-rebooked my connecting flight because my first leg out of BOS was delayed 1 hour. But when we deplaned at Amsterdam, everything was sheer chaos. I ran and ran through the airport, customs, etc on the chance I could get my original flight.. Got to the gate and my original flight AMS-BCN had not taken off. The gate agent was kind of uncommunacative by turned out he kindly found me a seat on my original connecting flight. As we took off the captain said... good news, we are in the air, and the rest of the flights today will be grounded. Bad news - there is no luggage in the hold! I was sooo happy I had only a carryon!) It turned out ok and KLM was helpful in this difficult situation.