Installation:

Download the plugin from SpigotMC.org
Place the plugin into the plugins folder on your server. By default this is located at '<Server Directory>/plugins/'
Turn on the server, once it is started turn it off again. This is to generate the config files
Configure the issue detection to be adjusted to your liking. If you don't know what you are doing here, the defaults are fine.
Configure the actions to take in response to each issue. By default only 'The Archive' (Logging issues) is enabled. You will need to setup the other actions to utilise them.
Read Server Assistant's commands and permissions page and assign the relevant permissions in your Permission Manager plugin (If you have one, if you do not then /op will be required to perform commands)
Turn on the server and use '/crashserver' and '/lagserver' to test that everything is working
Relax! Enjoy Server Assistant watching and looking after your server!