I see so many people trying to make things too fancy or go into way too much detail!
You need to keep your form simple as possible, and clearly present the incentive for opting in.
You only need their email address. You want your potential subscribers to opt into your list as easily as possible. (Unless you really want to personalize emails. then add the name field too)
When presenting your offer/incentive.. Make it stand out and be as appealing as possible! nice smart graphics help!
making your own can often make them look ameture and portray newbieness! (which isn't usually aimed for - unless people are following your journey out of interest etc.)
Try not to put too much information on there too! It will make the web form look ugly and stretched! People want to find out what you have to offer! rather then skim through a abundance of text!
Although, I have removed a webform from my sidebar now, and I have created a graphic with my incentive and a "click here" button. Which sends them to a squeeze page! The squeeze page then tells them what they are signing up for! And seems to work as they have already took action clicking the original button.
It seems to work quite well
Hope this helps,