There are more than 14 different theories out there that have been accepted as benchmarks for the study of second language acquisition. However, Freeman and Freeman (2009) have recently performed research stating how the processes for NATIVE language learning are no different than second language learning. Therefore, the best way to learn a second language as adults is through a) a low affective filter, b) a motivating and relevant tasks, c) consistent and immersed exposure, d) adding writing, reading, and problem solving tasks.
Chomsky, Bandura, Vygotsky et al would also agree that constructivism (building upon current knowledge, creating schema and what not) is essential for learning new skills and information. Therefore, rather than trying to re-invent the wheel, we should look at the natural and easy way that small children grasp, process and then produce any language given to them, and we should study that rather than going from the top down.
The Key word, however is low- affective filter! A.K.A= no stress