Hi and welcome,
It depends upon the time you'll dedicate to your studies. Anyway, the most important thing is Constancy. It is useless if you spend a whole week studying seven hours per day of Latin or Greek and then you leave it for a week or two. So, I'd recommend you to draw up a study plan and set your own goals in small stages. It's really frustrating to learn a language and not make any progress.
From my experience, when I've begun to fell that I was actually learning and making progresses in Latin and Greek it's been when I entrusted with new methodologies and methods. I followed some books which Textkit offers and they are in fact good (I am using now Sidgwick's Greek composition book). They teach a lot of grammar, &c., but after finishing some of them I wasn't able to read much Latin or Attic without the help of a lexicon. I use now Athenaze and Oerberg's Lingua Latina
series. These books teach Greek and Latin as if it were a modern language and when you go deep in it, you'll be able to write and read these two languages with ease. Again, constancy is important. ( http://vivariumnovum.it/Latino.htm http://vivariumnovum.it/Greco.htm