1. Lots of benefits near the point where the person has to make a decision to put in their email address. Opt ins haven't been a novelty for over 10 years. People are afraid you will spam them to death so you must make it extremely enticing for people to risk putting in their email address.
2. A blank field or fields that send the psychological message to the person looking at it that they should put something in the empty field. It's not a good practice to simply put a link to your opt in box or worse yet, have it as one of your regular navigation buttons. People will gloss over it there and many will never see it at all.
3. Not too many fields. The more fields you require someone to fill in, the less people that will sign up. You may intentionally want less people to sign up if you have to follow up with them by phone and you don't have enough people to handle all your leads. Certainly the more info they are willing to fill out, the more qualified they are. When simply giving away a free digital newsletter or download you want as many people to sign up as you can, so less fields to fill out is a better idea.
4. High on page. Your opt in boxes should be positioned high on your page... certainly so it can be seen in the first screen without scrolling. That doesn't mean you can't have additional signup areas further down the page, but in most cases we want at least one signup area on the first screen someone sees.
5. Multiple locations. Each page can have multiple locations to sign people up and you should have at least one sign up area on every major page of your site. Remember people can enter your site on any page. They may never see your home page so it's important to have signup areas all over the place.

Author's Bio: 

Alka Dalal, MA. , MS., (NYU and Rutgers University) with many years of corporate experience, founded i-Speak Consulting to enable individuals to take a pro-active approach in being effective communicators in the workplace. She has enjoyed success with different careers, family life and business. She is thrilled to share the stories of her struggles and triumphs in spite of adversities with others, to help them build their dreams and succeed in their own ways and finding their own creativity.She draws upon her vast experience to provide valuable tips on how to succeed in today’s economy using great tool called Internet Marketing.