There are multiple existing resources to assist with this skill:

Khan Academy Resources
Exponential function graph (method to plot a specific type of curve)
https://www.khanacademy.org/math/algebra/introduction-to-exponential-functions/graphs-of-basic-exponential-functions/v/graphing-exponential-functions

Algebra page - Math (including graphing)
https://www.khanacademy.org/math/algebra

Additional Resources:
http://www.bbc.co.uk/schools/gcsebitesize/maths/algebra/graphsrev5.shtml

I wish you the best on your exams!