The best email marketing allows to reach a huge target audience with minimal issues. The worst email marketing will leave you with complaints of spam and finally a list of email recipients you can't deliver to. The moral of the story is to go with a reputable company so you don't get left with a list of emails that you have to re-opt in at a later date causing you to lose valuable subscribers.
A lot of businesses are looking to promote their services online, and an email campaign often produces the highest ROI especially when coupled with other promotional methods. Advertising can often be expensive, if you can retain a prospect's email address then you have opened the door to much cheaper future communication and in effect cut the cost of your advertising. A lot of large companies already use email marketing such as amazon.com, paypal, and many other internet businesses.
Email marketing also allows you to monitor the results, see who opened which emails and which links they clicked. I'm sure you can imagine how useful that would be for you to be able see. Suddenly you'd have the ability to see what you can change to improve your overall sales at the click of a button.
Aweber provide a competitively priced professional service. Are they the best email marketing service? They have some of the highest deliverability ratios and range of features out there. They offer a great service for new and experienced email marketers. Other companies offer a different experience and some don't permit you to sell other people's products through affiliate links so it can be worth cross-referencing features to see what you need.
Most of these companies offer some kind of free trial so you can see for yourself which is the best email marketing service for you. Then the best way to get people to sign up to your newsletter is to offer a free information pack or something similar when they sign up. On Aweber you can test different styles of sign up form such as a floating form to see which gets the highest percentage of visitors to sign up. From there the next logical stop is to create a list of emails to send out to prospects over a period of time and calculate what sells the best. It's still a lot of work from your point of view, but your email marketing company makes sure that your work isn't being thrown down the drain.