Note: I almost always just include the email and digest options, but I've included the whole spiel for completeness.
<h2>Join the XYZ listh2> mailman/subscribe/LISTNAME">Your E-mail address: "text" name="email" size="30" value="">
Your Name (optional): "text" name="fullname" size="30" value="">
You may enter a privacy password below. This provides only mild security, but should
prevent others from messing with your subscription. Do not use a valuable password as it
will occasionally be emailed back to you in cleartext.If you choose not to enter a password, one will be automatically generated for you, and it will
be sent to you once you've confirmed your subscription. You can always request a mail-back
of your password when you edit your personal options.Password choice: "password" name="pw" size="15">
Confirm Password: "password" name="pw-conf" size="15">Would you like to receive list mail batched in a daily digest? (You may choose NoMail after you join.)
"radio" name="digest" value="0" checked> No "radio" name="digest" value="1"> Yes
"submit" name="email-button" value="Subscribe">