Don't save your new shoes for race day.
Don't pull a new pair of socks from their packet.
Don't start using a new lubricant or try double-socks for the first time during your race.
Your blister prevention intentions may be well-meaning
But you're setting yourself up for trouble!
Even if they're the same brand and model of shoe you've been wearing in training - don't pull a new pair out of the box on race day. Or even the day before race day. And maybe not even a week before race day (you don't get the chance to really test them on your taper). They'll be a bit stiffer than the ones you've been training in. The insole might be more flimsy than your last pair or creased at the edge and you don't notice it until you have an edge blister at the ball of your foot. Or maybe you won't have the right tension in your laces and by the time you figure it out, you've got a heel blister to deal with. Or they might be slightly different in some other way you can't even see.
Even if you know the new pair of socks you bought yesterday are more moisture-wicking than the brand you normally wear, leave them at home. There might be something about them that doesn't suit your skin. Or they might take up a bit more room in your shoe and squash your toes together ever-so-slightly too much.
You get the idea. All of this is bad for your feet because you're introducing a variable; even when you think you're not; and even when you think it's for the better. The outcome of these variables is unpredictable. Are you happy leaving this to chance - after all the training you've done and money you've spent to get here?
The real work with blisters
The real work with blisters is done in the weeks and months leading up to your event, not on race day. And not by the foot care volunteers in the medical tent, either.
Let me explain. If you see me in the medical tent, I've got a lot of tricks up my sleeve that can make all the difference to how the rest of your race pans out:
I can lance and drain a blister without it hurting
I can select the right dressing for your blister so that it heals ten times quicker
And I can drill a hole in your nail to release the blood in a jiffy (no, not with this kind of drill)
I'm saying this because:
By leaving your foot care to someone else, you're introducing variables. Remember I said variables are bad - because their outcomes are unpredictable. A different brand of tape, a different taping technique, a padding you've never used before. You can take these variables out of the equation by using your own tape, using your own taping technique, using the same thickness of padding you know fits in your shoe without making it too tight, etc.
By leaving blister care until you require blister treatment, you have at least three times as much work to do: antiseptics; blister dressings; monitoring for infection; donut pads (not always an option). I won't even mention the pain.
By leaving foot care until during the race and to someone else, you're wasting time in the medical tent. Or in the line waiting to get into the medical tent.
I'm talking about building a blister plan
The real work with blisters is done in the weeks and months leading up to your event. I'm not talking about reading a blog post or two, liking someone's blister photo on Facebook or throwing some bandaids in your blister kit. I'm talking about building a robust blister plan.
A blister plan is knowing which strategy (or combination of strategies) you will have in place at the start line for the blisters you expect to be troubled with. And knowing which strategy (or combination of strategies) you are going to have up your sleeve to combat unexpected hot-spots, so you can remain blister-free?