Okay, basically we all have different views on this.

IMHO: start with uncommons, feed the commons into the uncommons in the tavern.  Most uncommon are trash, except for Armiger and Saurus.  Some like the Monk.  You aren't going to need most uncommon champs, so use them as chickens.  You'll find later on that many Rares are trash too.  Figure out which ones you don't like and use them as chickens and 

Other than that, I would say don't use the brews unless you are levelling 4* or higher and don't have the energy for the campaign.  

1) don't use brews except for events/tournaments/etc

2) if you can afford to, focus on leveling 2* and onwards. you don't need to level 1*, but if you find you are running out of 2* champs, then you may end up having to.

And don't start with making new lvl 50's of the champs you want to use. Instead make food champs 5* first and get your your starter champ to lvl 60, so he can do 12-brutal.