I've found that 3-5 links, placed in specific places in the email, offer the best chance for a click through. The first one is usually the most-clicked, in my experience.

In the past, I've typically had pretty good luck placing the bare link in there, unless it's too long. Then I use the Google link shortener. But recently I've seen better click through rates with text links, so I'm going to stick with that and see how it goes.

However, in my opinion, it's not what the link says that drives a click through. It's what is said BEFORE the link. If you can set up your copy to pose a question, or tease about something intriguing or mysterious that can only be answered through the link, then by all means do it. Make them seek out the answer inside the link. Might be price, a great discount, a super bonus, etc. Might even be as simple as a statement like, "Isn't that what you're looking for?" Or "You REALLY need to see this..." They'll click almost without thinking, because "inquiring minds want to know."

Been using this for years and it still works like gangbusters.