Here are some pointers for beginners wanting to learn about Scholastic theology and philosophy. I hope my fellow bloggers will add their own material to this post.
1. Learn latin (otherwise, you'll be stuck reading Aquinas).
2. Learn the basic elements of Aristotelian logic: quia vs. propter quid demonstrations, parts of a syllogism (middle term, major and minor premises).
3. Read as much Aristotle and Augustine as possible.
4. Know the basic Scholastic genres: Quodlibet, Sententiae, Ordinary questions, Summa, various kinds of commentaries.
5. When you've done all this and are confronted by an actual Scholastic quaestio, consider the following bit of advice I have received from several professors but never followed: start by reading the determination [=the author's own answer/solution] of the question, then read the initial objections and their responses. I have never followed this myself, but it is good advice. Some scholastic questions can be bewilderingly complex (Scotus and Alnwick come to mind) and it is easy to get lost in all the back and forth. In my less lazy moments I like to at least glance over the structure of the question.
6. Read as much as you can by as many authors as you can find. At first the latin will seem weird and opaque if you are classically trained, but the amount of vocabulary is really quite small and the grammar is easier than classical latin. There are no dictionaries of scholastic terms (save for the Aquinas lexicon), so the best way to learn the Scholastic jargon is to read.