Don’t DIY unless you know what you’re doing!
Before you do ANYTHING, backup your phone’s data using iCloud or iTunes. I like backing up my phone using iTunes on my computer because I have limited iCloud storage.
iCracked provides an on-demand general mobile device repair service that includes cracked screens, and it’s available worldwide. They’ll come to you and fix your iPhone in 30 minutes for about $180 for a 6s.
You can also bring in your iPhone to an Apple Store for repair, which costs between $130 and $150 depending on the model. You’ll need to make an appointment and repairs take about 30-60 minutes.
If you know your way around a circuit board, then:
You can try doing it yourself with one of iFixit’s repair kits ($120) and online guides.