Wow, I totally missed this thread until now. Good tips from everyone. Take all of the tips here and figure out what works for you; that'll only happen with time in the backcountry!
I'll share some of my thoughts, in some kind of sequence of how things happen. Sorry if this gets a little preachy...
"beacons on at the car, off at the bar". Check your batteries before you leave your house. Carry spares. Do a full beacon check with your group, properly - everyone's send and receive. Don't skip it, even if you ski with them all the time. Keep other electronics away from your beacon. That means that if you're wearing your beacon in its harness around your midsection, your cellphone should NOT be in a jacket pocket.
If you're brave enough, try and at least partially de-layer before you start skinning. You'll extend the time before you have to stop because you're too hot. If you can't bring yourself to (I often can't, or not enough), do not be shy about stopping the group. Everyone else will be hot too. Don't let those layers get wet with sweat early on. I usually end up skinning in just my baselayer top down to about -10C (14F), but every day is different.
Experiment with how you want your boots buckled for skinning. For most people, it's much looser than how they ski, but it will depend on you and your boots. This year I am having to buckle my left boot down further than in the past, and I've got the layered blisters to prove it. Speaking of which, if you feel something starting to rub, deal with it. Don't wait, it won't get better.
There are a million ways to put on skins. Whatever works for you. I personally stick the tail of my ski into the snow, hook the tip loop of my skin over the tip of the ski, stick about the top half of the skin on, pull off my mesh (yes, I use it, because I hate pulling apart stuck together skins), then flip the whole assembly over, set the tip on the ground, clip the tail clip over the tail, and smooth it all down. Just keep the skin out of snow/fuzz/hair!
Use your heel risers. They're there for a reason, get proficient at putting them up and down.
Just like with anything, straight up may not be the most efficient way to get up the hill. If you're on your highest heel riser, the skin track is probably too steep. If you're slipping, it's definitely too steep. That may change depending on the snow conditions day to day. If there's another option, use it. Sometimes there isn't. Ski crampons can help, yes, but they're a pain and they're actually intended more for sidehilling than going up stupid steep stuff, but they work for both. Stay centered if you're starting to slip. Firmly planting your ski (like stomping down your foot) before transferring your weight can help. Taking smaller steps to reduce the weight transfer on each step can also help. If you're on a scoured or hard slope and your skins & edges aren't digging in, something like this may work:
Practice kick turns, over and over. Practice on flat, then on shallow slopes, and gradually getting steeper. If you're shaky with them on shallow slopes, you're going to be cursing them on steeper ones. There are many videos if you don't have anyone to teach you, this is just one. Actually, this isn't where I put my poles. Lots of different ways.
When I change over from skinning to skiing, how I do it depends on the location and conditions. What changes is how I deal with my skis. If I have a flat spot and it's not super windy, I don't take off my skis. If it's a slope or windy (where I can't set stuff down), I take off one ski at a time. That means I always have a ski I'm standing on so I don't sink. Here's my sequence:
-Lock my bindings into ski mode
-Stamp out a bit of a platform
-Take off my pack and change my layers into what I'm going to wear for the downhill, minus my overmitts.
-Put on my goggles (this gives my glasses, which darken, time to lighten before I have to ski)
-Take off my skins, either with my skis on or one at a time off, and put them away. I have been known to stuff them in my jacket, but they usually go in my pack.
-Put my boots in ski mode and adjust the buckles
-Make sure all my venting zippers are done up on pants and jacket
-Put on my mitts
-Ski!
Skins can be a pain in wind. I like this approach in theory, though I can see cursing it if I wanted to do more runs later.
When I get to the bottom of a run, if I'm going up again, here's my sequence:
-Stamp out a platform
-Take off my mitts
-Put my boots back in tour mode
-Put my skins on, one ski at a time (so I don't sink)
-Get my layers back in touring configuration.
I won't say much about avalanche stuff, other than to practice with your transceiver, probe, and shovel, and to assess continuously. Assess the terrain and the snowpack, even when you're not in avalanche terrain. Probe with your pole, do hand shears, etc.
Most of all...HAVE FUN!