Read up on
Definition 1 of 1
Pro Tip 1/3Purpose-Driven
Use 'read up on' when you have a specific reason to gather information. 
She's going to read up on gardening before planting her first garden.
Pro Tip 2/3Comprehensive Research
Implies reading various sources to understand a topic well, not just skimming. 
He read up on renewable energy for his science project.
Pro Tip 3/3Preparation Context
Often used when preparing for an event, a trip, or a discussion. 
Marie read up on local laws before attending the council meeting.