On the Beach
It really boils down to being aurally aware of what's going on around you.
Bit hard with CPDLC.
Jumpjim, we ask what is the highest level you can achieve for forward planning. If you say you can accept F XXX now, and by putting you up to this level NOW it opens a lot more options for separating others, we will probably do it. That problem is solved for us and we move on to fixing others. If you can't accept the level, tell us. The squeaky wheel gets the oil.
Most times we (the experienced ones) can tell when pilots are saying we can't take a level because they really can't or it is a huge stretch for them, or because they are trying to stay close to their optimum level, e.g. you have been in my airspace at FL360 for the last 2 1/2 hours (and have been flying for 7 hours) and tell me you can't accept FL380 ( I think you are a self centred git that is unwilling to divert from your flight profile to help out those around you). When I tell them that they will have to go down to FL 320 they do a recalculation and realise that they actually can accept FL380.
Who wudda thunk it?
Jumpjim, if it is really pushing the friendship say no. If it is not that great for you but achievable say yes. I have always tried to reward the pilot who helps me out with something better down the track. Saying that, sometimes nothing comes up down the track and the pilot feels that they have been dudded the whole way.
Sometimes your the windscreen, and sometimes your the bug!!!!