There are many things to consider when you choose a language or topic to study! You should definitely have a measurable goal, so you have something to work towards, and you should have a reason or motivation for studying the language. I think another important point to consider is how you study - your strengths and weakness, and the best way to learn for you. 

However, I believe when studying a language, the most influential point is to have fun and enjoy it! This may seem trivial to people who are studying 'seriously' rather than casually, but it can influence your ability considerably.

If you are just studying, just for the sake of studying, or you have to study it, then you may get easily bored and demotivated. So choose something that you enjoy- pick an area of study that you are interested in, use your favourite activity or hobby to study a language, as it will help you stay focused and make it more worthwhile. 

I always recommend, for learning English conversational skills, such as listening and speaking, to involve yourself with English resources that you like! Don't like a textbook- no problem! Watch TV shows, listen to podcasts, read articles, listen to music, watch movies, listen to audiobooks, watch youtube, or read books you like! There are a wide variety of resources that can make learning really enjoyable! I feel that this is one of the most important points when studying a language, to enjoy what you learn! 

What do you think is the most important point about studying?
How do you stay motivated to study?
Let me know in the comments or let's chat in a lesson :)