In answer to a correspondent:
Buy a set of NT Greek flash cards:
One mnemonic trick is that many English word are Greek derivatives. So, whenever possible, write the English cognate on the translation side of the card.
BTW, this also works for learning Latin. Unfortunately, it doesn't work for learning Hebrew :-(
Go through the flash cards until you've memorized all the words.
Buy an A Greek-English interlinear NT. There are several editions to choose from:
Start with 1 John. I recommend 1 John because:
i) The vocabulary and syntax is simple:
ii) The letter is short and compact, which makes it easier to master.
Start with chapter 1, reading one verse at a time.
Block out the interlinear translation with an index card and see how much of the verse in the original Greek you can understand/translate.
Whenever you hit a wall, refer to the interlinear translation.
Alternate between the Greek and the English until you can sight-read verse 1.
Continue this process with verse 1, &c.
After you can sight-read every individual verse of chap. 1, run back through the entire chapter from start to finish until you can sight-read the entire chapter.
Progress to chapter 2: same process.
Continue until you can sight-read the entirety of 1 John in the original.
Once you can read a chapter w/o the interlinear, buy a Greek NT:
From then on, just read the Greek NT version of chapters 1,2,3...
The above-cited edition also has a dictionary in the back in case you forget a word.
Purchase and work through Baugh's reader for 1 John.
This will give you some formal Greek grammar.
In may sound like we're doing this in reverse, and in a way we are, but it's more logical to learn how to sight-read the Greek NT and then catch up on formal Greek grammar than to rote-learn a set of abstract rules which you woodenly apply to the text.
Graduate to the Gospel of John. Repeat the same process.
Purchase and work through Walther's inductive Study of the Fourth Gospel.
Buy a simple Greek grammar such as:
At this point I don't see much value in investing in the major Greek grammars. The reason is this:
Greek grammars are presenting undergoing something of a revolution. In the computer age, it's possible to input every Greek text and then perform an exhaustive analysis of comparative usage.
So the major Greek grammars of the past, while still useful, are becoming obsolete.
Keep up with the latest developments at Gramcord:
Work your way through the rest of the NT. Save Hebrews for last.
Sample the LXX, using a Greek-English edition:
This is a quaint translation (there is a more up-to-date translation available, minus the Greek) without a critical edition of the text, but it will get you started.
Start with shorter units like some of the Psalms.
At some point you should bite the bullet and invest in the latest edition of BAG:
Branch out to Greek writers who are useful for NT studies or church history, such as Philo, Josephus, and Justin.
Use the Greek-English editions of the Loeb Classical Library.
Buy/borrow/photocopy the sections must useful for NT studies, like Philo on the Therapeutae, Josephus in 1C history, &c.
There are an increasing number of online resources for NT, LXX, patristic, and Classical Greek stuff which I haven't bothered to investigate. You can look into that yourself.