Links that are actions should be placed at the end of the sentence so that the user knows what they’re getting into by clicking on the link. Here is a part of amazon.com:
Because the "personalized recommendations" link takes you to the sign in page, I think that they should have made a link out of the words "sign in". Now, if they had done that, then their sentence would have looked like this:
Sign in to get personalized recommendations.
And a better version of this sentence would be this:
To get personalized recommendations, sign in.
As I read the first sentence, I have no idea why I might want to sign in while I am reading the link. But in the second sentence, I know exactly what’s being offered to me by the time I am presented with the link. The difference between putting the link at the end of the sentence and putting it somewhere else is like the difference between a waiter offering you the dessert menu when you’ve finished your meal and offering it to you while you’re still eating your appetizers. One makes sense; the other doesn’t.