Tips and tricks - OSGeo-se/swiss-army-knife-for-OS-GIS GitHub Wiki

Good to know if you want to work with Open Source GIS. Even some topic pages as QGis, Geosever and others.

Tip 1. Work with css instead of xml-based slds in GeoServer. http://docs.geoserver.org/latest/en/user/extensions/css/tutorial.html