Depending upon your target user segment, figure out what are their hangouts both online and offline, approach them personally and if thats not possible via emai

Depending upon your target user segment, figure out what are their hangouts both online and offline, approach them personally and if thats not possible via email. talk to them about your product, understand their perspective and try to convince them to use your product. For example say you are targeting college students, you can check out schools near your place, send out emails to college email group and get some feedback. f you are building something for developers, you can post it on HN and am sure you will get some useful feedbacks. All the best