Despite lots of confusing information out there, it is actually pretty straightforward to set a static address in Raspbian.
Being by editing the file (do not use
sudo vi /etc/dhcpcd.conf
Then all you need to do is append this to the bottom of the file, substituting the correct IP address and interface identifier you want.
interface eth0 static ip_address=192.168.1.141/24 static routers=192.168.1.1 static domain_name_servers=192.168.1.1
Restart your Pi to apply the changes.