Originally Posted by TheDoc

Simple is god! User/pass/email and join options does the best. Normally a centered form on a black background has the most submits. Sometimes all button forms do well on amateur style sites.

Too simple can kill it - so it must follow the site flow, some what.

No taller than 250px high header. All text (other than header) above the fold should be related to the transaction.. ie: secure, private, instant, fill out form - bam! Don't let them have wondering eyes - that pulls away from the form, thus lower submits.

If you put a back button up, more people go back... so drop the menus and make them use the back button. This also has a bonus, you can force fire a popup on exit if you know they have to hit the back button.

Put the promo shit and porn at the bottom, drop videos, flash, or anything that takes more than a split second to load.

Incentives work! Bonus sites, bonus time, rewards for longer access purchases, time limits work as well. DON'T LINK THEM!

Use a heat map to see where people go. Move the thumbs/text around to focus the clicks towards the form. That means the eyes are drawn towards it as well.

That's about all I got...