What is the best way to implement Mailchimp with Wordpress to get maximum email subscribers?

If you're using an organic way to collect emails, you can use any of the pop software's available in the marketplace such as optinmonk or poptin. If you have Google tag manager implemented in your website, you can directly deploy these popups using the GTM. If you don't have GTM, get a developer to implement it. Also, use an appending service such as B2Bdatapartners.com to regularly update your databases.

you can use the Pop-up feature or there is an extension to integrate forms on Word press with Mail chimp.

Implement the popup form feature. This will help with acquiring new leads

That depends on what you want to do with your subscribers. It may sound strange but recently for us, https://subscribers.com/ has been working at first instance. When the user returns for a second time then we ask them to sing up via Mailchimp's program. It's almost 2020, don't try just to steal or harvest peoples e-mails and throw a ton of spam, give them a value and a reason to love you and give away their e-mails.