It depends what you want to do. If you want to be able to write, I can't really help you. I learned the alphabet when I was really young, so it's second nature to me. If you're learning to read, the best place I usually start is children's books. There's a website somewhere with Persian children's books online. I also really love Persian poetry, and some of the more modern stuff will probably be more useful to you than the mediaeval stuff. If you want to speak, you'll need to compile a list of words and phrases that are most useful to your everyday life and translate them, and practice them a lot with someone who understands you. Once you've done that, you can move onto writing paragraph speeches describing yourself or telling stories you think are important. You'll need a persian person (or italki!) you help you here, because the internet is really awful at helping you learn persian.
i guess if you want something a lot more structured, you'll probably love rosetta stone. they don't use any english explanations for anything. just pictures and writing and recorded words. it's really effective imo, i just don't like that much structure.
there are also some children's school books people use. farsi avval dabestan should be where you start. these can only be bought in iran, but if you can find a local iranian cultural centre, they should have some.
there are some good websites out there to help you. easypersian is the best, imo.
dictionaries i use online are steingass and google translate, and italki as well. but the best dictionaries are the ones you can buy from iran. get one huge dictionary, and one smaller one with transliteration in it. or get one of those electronic translators that cost a few hundred dollars. i bought the lonely planet phrase book. that's okay, not fantastic, but it's a good all-rounder.
persian tv is really awful, but there are films out there you can listen out for. people seem to love kiarostami. also, if your persian gets good enough, you could start translating stuff like the persian national anthem and whatnot.
frankly, nothing's better for speaking than a tutor imo. having a tutor and speaking to them only in persian forces you to learn the words you use the most in your life.
that's most of my advice, really. good luck.