There's many opinions on how to install, which os to install on, and so forth.
There's some great videos on youtube that talk about how people run kamailio in their own environments:
https://www.youtube.com/channel/UCElq4JNTPd7bs2vbfAAYVJA
Although many people have different methods of installing the software, a great tutorial exists here:
http://kamailio.org/docs/tutorials/5.1.x/kamailio-install-guide-git/
The wiki is also a great place to find information on the software:
https://www.kamailio.org/wiki/
Good luck!
--fred