Avalanches suck. The photo below is from blatant early season stupidity, sick four years ago in Washington, rx resulting in a 1/2 to 1 foot crown and a 500 foot ride, a sprained ankle, a shitty walk out, and a super fun ER visit.
Tony Daffern has an excellent book: Avalanche Safety for Climbers and Skiers. Get the gear, practice with it, carry it. Still, evaluating conditions is more important than the gear. A beacon/probe/shovel is like a tourniquet - you want it in case you need it, but it's much better to avoid the broken femur in the first place.
Avalanche beacons cost $~300. The Mammut Barryvox and BCA Tracker are the current leaders, with digital, intuitive displays.
Probe poles suck. Get a probe (avalanche, though if you're into other sorts of probes that's fine, just keep it to yourself). $40 and 8 ounces. Also useful for figuring out if you're digging a snow cave into a boulder, which would lead to some tough digging.
Shovels. You need a shovel anyway, for digging a cave, a tent platform, as a platform for your stove, for collecting snow, for digging your friend out of avy debris. Black Diamond, Voile, and BCA make good shovels. Plastic, Lexan, and Composites suck, they'll break when you dig into said boulder, or just spontaneously. No metal, no good. Bigger is better (that's what she said).
Wear a helmet in avy terrain if you can. Head trauma kills a lot of slide victims.
And above all, think. Evaluate the terrain and the snow in real time. Dig hasty pits, be aware of sketchy layers. Don't forget about the snow thinking about the climbing or skiing or descent.
Mike and Allen's Really Cool Backcountry Ski Book is very valuable as a straightforward, effective discussion of backcountry travel, shelter, and cooking. Read it, it's very funny and very useful. Learn to build a cave, an igloo, a quinzhee, figure out how to store water so it won't freeze, and how to melt snow without scorching it (no joke). Includes information on farts, powerbars, and shelter.
Canister stoves suck. Buy a white gas blowtorch: MSR Whisperlite or XGK (the XGK is a man's stove. Sounds like an F-18).