Good question Lady TT. I think he mustn't panic or get down on himself for sure.
Nole has to regroup and refocus just a bit. But it's no shame to lose to a Federer playing vintage stuff. Boris Becker has to get Nole to realize that when the Federer genius comes out, that he shouldn't panic, ride the tide, and then look for opportunities to turn the match around. Easier said then done, but Nole has to have a bit more calm. He retrieves and returns as well as anyone. It will help him when he gets back on slower courts. These medium-fast courts in Dubai are probably just a bit too fast for him against someone with the ability and aggression of Federer when he is executing well. There is only so much one can defend, even for the best defenders in the world.
And it's not only Federer. Nole has to maintain his calm against whomever his beating him, whether it be Rafa, Andy, or ?
He also has to try to avoid these irritating lulls in a match, but then, that is tough for any player, especially in a five set match. One just to find ways to limit those lulls as much as possible. I don't know if Nole hired Becker to help him on his net and overhead play, but it might be a mistake to try and change his previously winning formula now. I think Becker needs to emphasize that Nole should try to stay calm and steady throughout the match and maintain his level as much as possible.
Respectfully,
masterclass