Be a better climber on toprope than you'll ever have to be on lead.
If you can hike any piece of vertical water ice on the planet on a toprope then you're not going to be losing it too much leading a 70-degree pillar. Put another way, be better in training than you'll have to be in combat, 'cause I can guarantee you that you will NOT perform better under pressure than you will in training, at least in any sport that requires fine coordination like climbing. Running or other aerobic sports maybe, but if you haven't trained to an appropriate level then you won't perform well in competition. And your training had better look like a performance day; lifting in in the gym will not make you a better athlete unless you can use that strength...
In rock climbing the solution to most pumpy, difficult situations is to simply try harder and keep moving. I watch rock climbers on ice do this all the time; most ice climbs just aren't all that steep, even the "grade 6!" hype. Stop. Put both tools in. Get some good feet. Shake out. Stem a bit. As the pump drains your mind will open up. Put in a screw. If you're really messed up clip a quickdraw into your belay loop and put the biner on the BOTTOM of the handle, either through the hole or over the pommel. Rest. Once you're mentally back in control start climbing again. It's actually the swinging that is the pumpiest thing about fresh steep ice climbing, if you just slow down and focus on finding either a natural rest or one on your tools then life will be far better.
Climb down two feet.
I've watched leaders turn into mental gerbils while wrestling with a tough bit of climbing when all they had to do was climb down two feet to a rest and look at the situation from a slightly different viewpoint.
Don't start until you can see it.
Look at the climb. Figure out where you'll start swinging, where you'll get a screw, how you'll pull the bulge, where you'll belay, what the tough bit is likely to be and how you'll deal with it, how many screws/slings you'll need, how you'll climb, etc. Then close your eyes and run the climb in your head. If you can see yourself doing it all then you will. If you can't figure it out. Have a couple of plans about how you're going to deal with the ice; "If that's bad I'm going right, but if it's good I'm going right over the top."
No matter what sport you do the person doing more of that sport will likely be better at it than the person who does less of it... Ice climbing is hard to do a lot of unless you live near the ice, but there's no other way to get comfortable than to climb a lot of it. A two-week trip will likely make you a far better ice climber than 10 days spread out over two seasons...
And some other stuff, but I gotta go now. Give 'er!