I learned using Mounce's textbook and workbook (and occasionally some of his videos). I found his method helpful, though haven't used his materials in Accordance at all.
I don't think I'd recommend taking first steps in Greek on a computer--better probably to puzzle it out with some vocabulary flashcards and a good textbook and paper workbook that allows you to actually practice writing Greek letters and words and verses with your own hand... and using a lexicon to get the feel for looking up words manually. And, of course, as Joe mentions, a teacher, if possible--if video lectures are all you can access, that can certainly get the job done.
Of course, that method is being questioned now by many who urge the "living language" or immersion model (like these folks). In fact, depending on your preferred learning style, you may find some of Buth's stuff easier to engage (and more effective) than Mounce. What I've sampled of his "Living Koine Greek" looks good. I've certainly appreciated the Hebrew materials he puts out, and own one of those books.
You could also start small with Zondervan's Greek for the Rest of Us (also by Mounce). I don't know much about it, but it might be a good baby step to see how far you want to go in Greek before you commit time, money, and resources to it.
Learning Greek (or any language) is hard work, so I think it's also important to clarify from the outset what your motivations are for learning the language, and what you hope it will help you achieve in the end.
This has come up before on the forums, and folks seem genuinely happy to chime in on the topic, so keep asking about it! I'm sure a number of forum users could comment on the Mounce program in Accordance.