Tips & Tricks for flying and also getting the most value?

[NoServersInTheCloud]

Hey everyone,
Im flying British Airways direct to London for a work trip in a couple weeks. Flying Economy, but I am able to put my own BA Frequent flyer membership in for my ticket.
What are some tips and tricks you all recommend to get the MOST value (not cheapest, but value, maybe fastest way to get upgrades, etc.) possible for flying, and also maybe general tips and tricks to make the flight more comfortable.

So far I've done the following:
1. Added my British Airways membership number
2. I have a Discovery Black card to skip the security queue
3. Work Card and Discovery card for international lounges at the airport

Not sure if it matters, but Im 23 (maybe there are weird extras for younger people).

 

[I.am.Sam]

you get to join the mile high club for free - use the passcode sexintheclouds

 

[Sinbad]

Go to the airline counter before you check in and ask if there's any chance of an upgrade.

 

[SauRoNZA]

Seatguru is your friend.