I would recommend that you get yourself the Basics of Biblical Greek workbook (it shouldn't cost more than $15 used) and work all the way through it. It's a lot easier to learn from than many of the older intro grammars. I've got a list of suggested resources here that may or may not help:http://www.greekingout.com/new-testamen ... resources/
A good workbook is still not a tutor, but it can be a decent substitute if you don't have access to a living, breathing teacher or tutor.
Also, if you struggle to retain what you learn in the textbooks, I recommend that you spend some time just reading easy NT books like 1 and 2 John out loud as often as possible in addition to the work you're doing in the grammar. It's amazing how much this can help you to internalize the grammar and morphology you're learning - even if you don't really have much comprehension of what you're reading.