best ways for english speakers to learn german online

Hello, I am learning German as of right now and would like to know what resources might be most beneficial to native English speakers.

additionally, any counters to Petrov's defense would be appreciated as well.

danke. i am using duolingo right now, but will look into rosetta stone

Like every language, you have to use it. There are no real tricks. Just choose the learning software you like the most and keep practicing practicing practicing. 

Against Petrov, Steinitz d4 of course

Just practicing using any learning platform, additionally watching German videos,TV shows and listening to German podcast will probably help too, you can also go to Austria or Germany for holidays and try to speak to the locals