@tami "You mention four skills - speaking,  listening,  reading and writing.   I don't know where vocabulary fits in there or if it should be considered a fifth skill, but without it we have none of the others."

Vocabulary comes hand in hand with the four skills and shouldn't be separated. We can't study vocabulary without reading, writing speaking and listening. Learning vocabulary separately from a skill removes learning in context and we learn best in context. Of course create flashcard sets after you've read or listened to something, but those flashcard sets need to be in context. 

A great way to learn new vocabulary is to choose a topic of interest. Then subscribe to a podcast or magazine or youtube channel on this topic. Then you can write new words down, look them up in dictionaries, put them into flash card apps like anki. For example you could create a flashcard set on cycling, pulled from an article you've read or a podcast you've listened. You could learn new vocabulary around cycling fitness, or parts of the bike, or places to cycle, or cycling lingo. In this way we are learning new vocabulary whilst at the same time improving our listening and reading skills. Once we've improved our input skills we are ready to output them; speaking or writing.

Here's my opinion:

The title "Simple Trick To Master Any Language In 6 Weeks" is very annoying and misleading. It should be something like "5 tips for learning languages".

Tip #1: Review your work outside of the session - Good tip. A better, more general one might be just to review.

Tip #2: Keep a language learning folder - This is probably more appropriate for someone taking classes than self learners. Keeping some sort of database for stuff you've learned, for example an anki deck, is a good idea, but time-consuming, so I think one needs to weigh the pros and cons.

Tip #3: Practice all four skills - Absolutely. I would add pronunciation, grammar and vocabulary to the list, and make it clear that it's not necessary to spend equal amounts of time on each one. The important thing is to get as many parts of your brain as possible to work on learning the language.

Tip #4: Focus on the small goals - Imo, it's not necessary to set goals at all. There's nothing wrong with it, but it's a matter of personal preference.

Tip #5: Try and have fun! - I get sick and tired of hearing this one. Certainly not a requirement.

Yes. You may pay money and learn main models of a languge in 6 weeks. And what is interesting people, who will have an interest of understanding you, will understand. I say 'an interest' because you speech will be produced with a huge accent and there will be little wishers to do the understanding. But the main trap is that you will not be able to understand what people would talk back. So, with the help of mimic there is a joke among the beginners - 'After our lovely conversation my arms and fingers got ached.'

Among 'four elements' the main is istening. It take much more time than 6 weeks. Some children continue their listening for a whole year or even two before starting to speak. And that is in a complete language environment.