Updated: May 19, 2020
Getting into presuppositional apologetics can be difficult. The best way to describe presuppositional apologetics is as the application of Reformed theology to unbelief. The most popular and arguably the best representer of presuppositional apologetics to date would be Dr Greg Bahnsen. There is a 4-part series by Bahnsen titled 'Van Tillian Apologetics' that is available for free on the Westminster Theological Seminary's website. This is the best place to start your journey. Lecture 1: An Introduction to Presuppositional Apologetics / Van Til's central thrust in apologetics. Lecture 2: Van Til's life and legacy Lecture 3: Van Til vs other reformed thinkers (Schaeffer, Dooyeweerd etc.) Lecture 4: Van Til and theistic proof.
These lectures are incredibly useful and correct a ton of misconceptions when it comes to presuppositional apologetics. Do presuppositionalists ignore evidence? What do we make of the classical Christian arguments? Bahnsen will more likely than not completely blow your mind with what he has to say. So take the time and hear him out.