Mounce's second edition had three great characteristics: 1- Smaller in size; 2 - Direct to the point; 3 - It had a Cd with audio summary lectures. The third edition has none of it. (I have both of them!)
After you read Mounce two or three times, get a copy of Learn New Testament Greek third edition by John H. Dobson. You will see in practice what you learnt from Mounce. It will help you a lot in your reading.
For homework, I preferred the following two books: Learn to Read New Testament Greek, Third edition, by David Alan Black and Learn to Read New Testament Greek - Workbook: Supplemental Exercises for Greek Grammar Students by Ben Gutierrez , Cara L. Murphy and David A. Croteau.
I found three other very important materials as helpers: 1- The Complete Vocabulary Guide to the Greek New Testament by Warren C. Trenchard; 2 - Sing and Learn New Testament Greek: The Easiest Way to Learn Greek Grammar [Audio CD] by Kenneth Berding (Great!); 3 - Biblical Greek Survival Kit by William D. Mounce (it includes Basics of Biblical Greek Vocabulary Cards + Basics of Biblical Greek Vocabulary Audio CD (also in mp3 format) + Biblical Greek Laminated Sheet Zondervan Get an A! Study Guides).
For your reading on NTG, get a copy of: A Reader's Greek New Testament: 2nd Edition [Leather Bound] by Richard J. Goodrich and Albert L. Lukaszewski. This is for building vocabulary, not to know the "correct" reading of the text.
The three important New Testament texts are: 1- The Greek New Testament with Greek-English Dictionary, 4th Revised edition, Edited By: Barbara Aland, Kurt Aland, Bruce M. Metzger, etc.; 2- Novum Testamentum Graece 27, Edited By: E. Nestle, Barbara Aland, Kurt Aland; 3- The New Testament in the Original Greek (Greek Edition) by Maurice A. Robinson and William G. Pierpont.
If you have no idea what Textual Criticism is, get a copy of: New Testament Textual Criticism: A Concise Guide by David Alan Black.
After Mounce, Dobson and Black, look for two other books: Greek Grammar Beyond the Basics by Daniel B. Wallace and A Workbook for Intermediate Greek: Grammar, Exegesis, and Commentary on 1-3 John (Wood Sermon Outline) by Herbert Bateman IV.
Remember, there is a great difference between learning NTG and translating it. Do not confuse them!
About a dictionary, you do not need something fancy in the beginning, but this is the big deal: A Greek-English Lexicon of the New Testament and Other Early Christian Literature, 3rd Edition by Walter Bauer and Frederick William Danker. - If you can find a good used copy of the second edition, it will be great.
There are a lot of materials out there to learn NTG, but if you cannot buy all of this, do not worry, get Basics of Biblical Greek Grammar by William D. Mounce.
Do not give up!
charis humin kai eirene apo theou patros hemon kai kuriou Iesou Christou.