What is the best way to get customers to sign up for email, loyalty program and texting?

[PetitParker]

I currently have both email and a rewards program through square but it only allows you to get information at the end of a transaction for ONE of the options.  Is there a way to sign someone up for everything that is as easy as pushing the "sign up" button?  How do you capture a customer for both email and loyalty?  Any ideas?  I wanted to get this done before adding in "text" option.

[Doran]

I use a multi-part strategy.  

A 15% discount for online signups.

At the cash wrap, it is on the customer-facing checkout screen of my register.

I also offer a special GWP throughout the year for signing up.  Usually during the slow seasons.  

I have a sign by the checkout and in the changing room to sign up on our website for 15% off their treatment that day.  

Also, at the bottom of my emails I always include a blurb about forwarding this to a friend they think will love our shop or blog.

[alexandriak]

I don't know that there's a one stop shop way to get them signed up for everything in one go UNLESS you do it manually. 

I'm thinking you could create a form on your website to collect all the information and then you can manually add them to each program. This could be time consuming though. I would like to see something added thru square for a customer to sign up for everything a store offers in one go.