What is the easiest way for an average adult to learn a new language?

Make a list of the 100 most commonly used phrases.
Memorise them, draw pictures of how they 'sound' to you
Draw pictures of when/how they are used
Get a picture book and try explain it in the words you know

Rinse, Repeat...add more pictures.

I use this method to learn Swedish. It's from a book written by a guy I can't recall this minute, but he learnt over a dozen languages
linking sounds to images