It doesn't take much to cope with non-standard surfers.

[Head Boy]

There probably aren't a lot of webmasters who tutn off animations, but why not make the first frame of your animated banner a reasonable static image. A black rectangle isn't going to get you any hits.

Don't make that picture in your post too wide - people don't like to scroll right, so you will probably end up with a partial display, and part of your text missing.

Some of us have secure server alerts. If you serve your banner from a secure server, then it throws up an alert, and you get put on ignore. As the major culprits of this are spammers, then it seems mad to create a sig that reduces your exposure.

If you have a large popup box on your text link that obscures part of your text, then you stand a good chance of having both of them ignored, and maybe a quick exit from your site.

If your whole page is one massive table, then your visitor will probably be gone before its loaded.

I expect there are some others, but that will do for now.