On the main question about economy seats, the answer lies in your preferences and how much extra you will be prepared to pay for the nicer seats. LH does not offer Economy Plus, it's Premium Economy and it is broadly equivalent to what US airlines call First Class, but with better food and wine. If you can sleep in a regular economy seat, it's not worth it at all; if you can't but can in a Premium Economy seat, then it's really worth it as the first day of your trip won't be so awful. But the truth and the value will lie somewhere imbetween.

As to tricks, avoid making jokes about bombs with airport security staff.....