Even the best method of learning foreign languages, as well as selection of one of the best schools in the city, may fail when we are trying to learn a new language, without following a few simple rules.

An important element in learning anything, is being systematic. Without being systematic, effectiveness can be much smaller than we expected at the point where we started learning a foreign language, or other skills. It is also important to learn systematically, not to overstrain oneself during a single long session. The learning process that overstrains us will never be effective. 15-20 minutes every day is a better learning solution than reading English guide book once a month for a few hours. In addition, a scientifically proven theory says that when we do something systematically over a period of 3 to 4 weeks, we fall into the habit of this activity.
The main problem for people trying to learn something new is losing motivation. Learning by using one method, eg. by reading only a purchased book, will be wearying after some time. In the case that the chosen method is getting us bored, we have to replace it with a new one, that should help us not to lose motivation for further learning. When you are learning a foreign language, you should also keep in mind that many forms of entertainment such as watching movies with the original soundtrack, or listening to music in a language which we are currently trying to learn, can also help us eg.  in the correct pronunciation of words.

Source: http://szybkanauka.pro/jak-uczyc-sie-jezykow-3-zasady/