I don't market time.
However, I do try to avoid buying what I feel are excessively overvalued stocks, and I have been known to sell them when I feel they become excessively overvalued. Key word here is excessive. Think Cisco at 60 times earnings. At 30 times I'll give it the benefit of the doubt.
I was only about 50% invested in the tech run-up and meltdown in the 1999-2001 because I sold some stocks that I felt had become way overvalued and couldn't find anything to buy.
I bought somewhere in the middle of the way down, and kept buying as it dropped (and then on the way up). It turned out well.
The market doesn't strike me as a screaming bargain, but it doesn't seem overvalued either. There is a lot of uncertainty, and the market valuations reflect that.
If we have to live through a 70s style recession, we will have wished we sold today, but if we just have a regular garden variety recession, selling seems silly. Those are over in a year or two. No big deal.
Since a regular recession seems a lot more likely that a repeat of the 70s, I'm steadily buying just like normal.
Even if the bad one comes, by the time we're in it it will probably be too late to do anything but dollar-cost-average through it anyway
I'm starting to understand why some of you own bonds though. Maybe I'll buy some when I hit 40.