Because of the advanced nature of systematic theology in general, it is not a good idea to study systematics until one is ready. These are the recommendations I usually give to people who consider jumping into this study. I do not think systematic theology is a matter of salvation, so one need not be concerned about that; however a level of understanding is needed which some may not yet have.

If you are ready to study systematics, then I strongly encourage you to do so. Remember that the whole point of theology is to learn more about God, our relationship to Him, and to respond to those who spread error; systematic theology is but one branch of theology that facilitates these directives!

With this in mind, I consider these prerequisites critical to studying systematic theology in general, and of course Arminianism in particular:

• A willingness to set aside prior doctrinal beliefs and presumptions when corrected by Scripture. (As I like to say, "I shall bend to Scripture as a reed bends in the wind.")
• One has read the entire New Testament.
• One has a firm understanding of the fundamental doctrines of Biblical theology (e.g. grace, the Deity of Christ, etc.)

I consider these very helpful, though not essential to studying systematic theology:

• One has read the Old Testament
• One has learned or is learning about the socio-historical background of the Bible (e.g. shame and honor, Jewish tradition).
• For studying Arminianism specifically: one has a basic understanding of what Calvinism teaches. I recommend Matt Slick's presentation of TULIP here.