Tips for evaluating coupons - suggestions?

Obviously I'm quite new to the coupon world, but as I have been reading various posts about coupons I see some people have mentioned evaluating the coupons. So my question is, how do you evaluate a coupon - especially a coupon from a network? Isn't all the information you need to determine if it's a good coupon right there (i.e. - commission amount, expiration date, links, HTML code and etc.)? I'm just wondering if I'm missing something...

is it applicable to your audience? is it timely? is it easy to use (not 50 characters long to enter the code) or does it apply automatically (by simply clicking on the link).

Bonnie, what do you mean, is it timely?
And to everyone, is there a way to check if a coupon code is valid without going into the checkout process for the product in question? Not that I mind doing that, I'm just wondering if there is another way.