There are 2 editions of
Calvin's Institutes; Beveridge Edition (older) and the Battles (Ford Lewis) edition (newer). I have both and personally prefer the Battles edition which I found easier to read due what I think is a better translation of the French. YMMV

Another classic is Lorraine Boettner's
The Reformed Doctrine of Predestination, a long time loved volume in the conservative Reformed community. Should be easily found.
Methinks a common mistake when studying theology, and also the Bible is thinking that one can grasp everything in one reading. My advice is always to read through these things completely, from beginning to end and then return to specific sections and delve in with a more focused study. This is most true in regard to Scripture. Do NOT ever think you will be able to comprehend everything contained in God's inspired Word even if you would live to be 5000 years old.

How can a finite creature ever comprehend the knowledge and wisdom of the infinite God?

Even in eternity on the New Earth to come, no created being will be able to comprehend the depth of the wisdom and knowledge of God. Add to that the noetic effects of the Fall and the fact that God has given to each according to His grace the ability to comprehend anything of God. The Spirit will reveal that which God desires you to know at every step of your journey.

Lastly, if you have at this time a desire to prepare for the Christian ministry, which is an entirely different subject, there are a couple of essentials which you need to consider:
1. The testimony of the Spirit, both within and without, i.e., the wisdom of others members of a church and the scrutiny of the Elders of a sound church. Sadly, there are not many sound denominations left in our day nor individual churches that could advise you. Thus BEWARE of the source(s) you put your trust.
2. Get a formal education in the faith, particularly strive to learn the original languages; Hebrew and Greek. Have your theology down fairly solid BEFORE you enter into any formal institution. All things must be brought before the light of Scripture and tested and not given approval just because someone has a Ph.D and/or is very popular. Too many are of the mind that if so and so saId it, it must be true.

There are men who have earned the deep respect for their knowledge of Scripture and who have lived holy lives, e.g., Calvin, Owen, Edwards, et al and more recently, men such as William Hendriksen, John Gerstner, et al. NONE have been given infallibility and thus have erred from time to time. Pray for discernment!!