I'm a fan of Hardenize. I like using that site to help people understand what needs to be done.
The especially frustrating thing is that there's no way to find out why you've been binned. Even my friends who work at Google can't find out for me, much less get me whitelisted.
This doesn't change the problems of unreliable email because mail services are too aggressive, unfortunately.
We recently got a bounced mail (not dumped in a spam folder, actively rejected) from a major university, telling us that the message looked like unsolicited bulk mail. The message was sent directly to a specific single customer in response to a purchase they had just made, contained information that we were required by law to provide to them, and was sent from a reputable host with things like SPF properly set up. That is simply broken, and it is 100% the fault of the mail service admins at the university.