Hmm... seems like the future is the most important thing missing, which I find surprising as it was the second tense we learned after present, as it's very easy (just stick a sigma in the ending
). The only thing is that of course its passive forms (just like those of the Aorist) are different from those of the middle case.
So if you can I'd just take a look at the future and plusquam perfect (that's easy too, but not as important as future).
I think you could start translating a text, as I said Lysias or Plato for example, but really what ever you fancy. I would suggest you buy a small grammar, if you don't have one already.
I have a very concise Greek grammar (and a really large one), but I find the concise one very good for reference. When you're translating an original text first time and your main goal is to translate and understand the text, then you don't really want to have to go through a huge book just to find out what the various uses of the optative or conjunctive in Greek are or how to translate many negations or even if you just want to look at the various tenses again to make sure you've analysed a form correctly. Uhh.. and of course you'll need some dictionary.
If you aren't too sure whether you really want to pay out for an expensive dictionary, then search around for readers, which have all the vocab you'll need for that text at the back of the book.
So maybe you'd like to start with:
Plato's Apology of Socrates and Crito in Greek, Louis Dyer
Easy Selections From Plato, Arthur Sidgwick
(you can download them here at textkit in the Learn Ancient Greek section) and if you have any questions about any sentences you can always post your questions here