I think I'm averaging about one of these every week since October. Adult deer ticks - the ones you find in cool weather - are more likely to be infected with Lyme Disease than the summer nymph stages. Fortunately, most people either feel the tick walk across their skin or they will feel an irritation after the tick bites. I usually find the adults walking down my arm, often while driving back from a hike through heavy brush. Or they might be on my neck, behind my ear, or on my back. And I always pick the adults up in the brush, so it's easy enough to do a tick check after letterboxing or working in the woods.
I've heard a lot of stupid things about ticks. Some come from medical professionals. For example, a friend of mine pulled an engorged tick off of herself in the winter (surely an adult deer tick) and called the doctor. She was told that if she could see it, the tick couldn't be a deer tick. I've also seen on the Internet pages that say it is all but impossible to see the nymph ticks. Hello? Ticks are not invisible nor are they microscopic. I can see the adults and nymphs just fine, and I occasionally even see the larvae, which are way smaller than even the nymphs (larvae can't carry Lyme Disease). The point is you need to LOOK very carefully and use mirrors and/or partners to check the areas you can't normally see. And I suppose if you are very hairy or have darker skin you're going to have a harder time.
The nymphs are a summer thing (May-June-July), and that's how most people get Lyme Disease. I think this is only partially because nymphs are smaller and more difficult to see. I think it is also because nymphs prefer low vegetation and grassy areas rather than brush, and people pick them up just by going out to their BBQ or mowing the lawn. They don't think to do a tick check just for stepping out onto the lawn.
Outdoorsy people, however, check for ticks constantly, and investigate every little tickle that might prove to be a tick. As long as the tick is pulled off within 24-48 hours after a bite, you won't get Lyme Disease, even if the tick is infected (and chances are good that it is not). Knock on wood, I've pulled hundreds of deer tick off of me over the years but never got Lyme Disease.