Plus, I almost never plunder for profit these days either. Only time you`ll ever want to do that is if you come across a U class planet (collective can`t use em), or a cluster (which can`t be used to produce food unfortunately). Otherwise, you try to acquire 800+ land barrens and make good sized clusters to produce food.
One more piece of advice. It takes a LOONG time (depending on luck) to make a good collective c3, and the more your base PR rises the less you`ll capture good planets. Once your base pr gets over 100k pr, you will spend all your time on battling and hardly any on research. So take your time and RESEARCH while you can. You`ll be glad you did later when you base pr gets higher (assuming you don`t die).
And be active. If you slip up, thats the end of your empire.