I have a breathing tip. Make sure you exhale completely before inhaling. Get that last little bit out by pulling in the diaphragm, like "breath of fire" in yoga, you'll hear that puff at the end. This will let you make more room for air to come in on the next inhale, which you want to take in as slowly and fully as you can. If you're gasping, you're not getting enough in because the old air is still in there.
The other thing is to smile and relax every muscle you can. If it's not helping climb, it shouldn't be tense. If it's tense, it's taking energy away.
'02 Eddy Merckx Fuga, Selle An Atomica
'85 Eddy Merckx Professional, Selle An Atomica
'10 Soma Double Cross DC, Selle An Atomica
Slacker on wheels.