What does my website need to be able to work with LastPass?
While LastPass can work on most website logins, if you are developing your own site you can help make it LastPass-compatible by using a simple form submit with a username, password, and submit field.
Here's an example:
<form action="https://mypage.com/blah" method="post">
<input type="text" name="username" id="username" value=""/>
<input type="password" name="password" id="password" value=""/>
<input type="submit" value="LOGIN"/>
As far as what to avoid -- always create the form on page load, even if you hide and show it to people clicking log in, it's better to be there on page load. Avoid AJAX for logging in and avoid method=GET.