Generally, people don't prepare for SNAP separately. The preparation is done with the help of CAT materials since the concepts are same for both the exams. For SNAP, the most important thing is speed and that can come with enough mocks. Take SNAP mocks and give enough of them until and unless you are happy with the speed and the marks scored. The objective should be to able to see and understand all the questions at least once and attempt as many as possible.
I found TIME and IMS SNAP mocks to be quite helpful.
SNAP preparation strategy:
I am also giving you a list of Top 10 institutions with neither take into consideration of the CAT score nor the past academic track record, so keep a watch out for them:
Also tips on how to improve the profile:
Hope that it helps