In general, the less opt-in fields, the better your conversion rates will be. The most commonly asked information is “First Name” & “Email”
The debate about asking or not for the first name is long and complicated (and if you are interested in the topic, I urge you to read this article) but general rule of thumb:
If you personalize your emails, ask for the first name. If you do not use this information, only ask for the email address.
Opt-in Rates Vs. Targeting
That said, you might be the exception! Maybe you don’t want to have the highest opt-in rate possible but only target highly relevant leads. In that case you might consider adding obligatory fields such as “Name” or “Phone number”.
If you don’t NEED this information right away, but you would love to have it for further marketing efforts, I suggest you ask for it after getting the email address.
Imagine you would love to be able to send birthday gift cards to your leads. This information is not necessary upon opt-in. You can ask for it later on in