I find the best way to chose them is to ask for recommendations. But if you do want to just browse and pick one up -- check the byline. If you do not recognize as a published author's, check the about-the-author note. Ensure that the writer has actually published something other than a how-to-write book.
And then, of course, you read. While you read, remember that the author is sharing his bag of tricks with you. If he's an editor or an agent or someone who taught writing, he may have a large repertoire than someone who just writes. But regardless, the techniques he uses are just tricks you can try, to see if they work, and discard if they don't. Experiment. Do writing exercises. And stick to what works.
Some writers are quite insistent that you do it their way. That's when you use the salt-shaker to take it with plentiful grains of salt. Some, in fact, get quite silly. One book said that first you chose your genre, and then you work on a "what-if" and hammer it into shape that fits that genre. Especially if it doesn't fit that genre originally. Why not change the genre? The book doesn't even touch on it. Now, if the what-if would only fit a genre you don't like to read, that's one thing, but why must you stick to your genre if you don't get ideas for it?
Then, of course, there's always the little problem that reading how-to-write books is an excellent way to vacuum the cat. Put all those techniques you are trying out to work. It will give you real standards to judge them by.