Hi Anonymous,
For general advice how to improve graph reading, the GMAT chapter for integrated reasoning is a good ressource (I believe it was added 2012 or 2013 to the GMAT, so you can take any GMAT ressource after that period).
Apart from that: practice, practice, practice.
Hope that helps - if so, please be so kind to give it a thumbs-up with the green upvote button below!
Robert