Some companies insist on paying by check and that typically works out as long as it's a company check I wouldn't worry too much. I would avoid personal checks or if you get a funny feeling about a client.
Stripe would be another option, you could even create custom invoice pages on your website for clients with the stripe payment form embedded on the same page as their invoice. (You'll need an SSL certificate (HTTPS://) for your website stripe requires it. You can sign up for Hostgator's Business plan for $15 and they include an SSL cert free upon request.)
I also recommend getting a 25% payment up front and breaking the project into multiple milestones where you receive payments and they review the work incrementally to make sure everyone is on the same page and you won't get left holding the bag waiting for a large payment at the end of the project.
Good luck with Freelancing.
On the other hand, Square is extremely convenient and free to use (other than a per transaction percentage charge).
The one time I broke my rule and accepted a personal check, I got burnt. I'd advise you to only accept certified funds.
https://www.paypal.com/us/webapps/mpp/security/chargeback-gu...
comment for the OP not you _pius