The worst enemy any serious student of music must face and overcome is overwhelm. The sooner one comprehends this debilitating mental state, the better. Too often, it seems as if there is just too much to know and too much to learn. The deluge of material one needs to absorb to become an improvising musician is indeed immense and infinite.
However, you must not allow overwhelm to take over and control your thoughts, especially when you are practicing. If you are in the midst of learning a particular passage, or learning a specific ii-V line and you are thinking about how you suck at playing in 7/4, then you are in a state of overwhelm. This is a mild case, but there are some individuals who get so crazy about everything they need to know, nothing ever gets done. The key is to recognize when you enter this self-defeatist frame of mind, understand that it is your ego working against you and get back to the task at hand.
While overwhelm is your worst enemy, routine is your best friend. Routine is of the utmost importance and the more routine you are in your practicing methods, the quicker you will progress. You should know exactly what you are going to work on before settling into any practice session. In fact you should know this the moment you wake up in the morning, and if your approach is methodical, it will be an extension of what you worked on the day before.
Let’s be real, the more you practice, the better you get. I don’t think this is a shocker to anyone. It is, however, better to practice 2 hours/day, rather than 5 hours one day and ½ an hour the next. The latter signifies that your approach to practicing is not routine or methodical. If you are going to school it is perhaps unrealistic to think that you can put in 8 to 10 hours a day. However 3 to 5 hours seems reasonable. Plan ahead and set up a schedule at the beginning of each week. Let’s say you intend to practice 4 hours/day for 6 days (it’s ok to take a day off here and there - keeps you “hungry”). Break down the 4 hours into categories such as technique, transcription, learning lines, learning tunes, etc. You can further break down these categories into sub-categories. Be very clear and specific as to what you are going to work on. Understand also, that to effectively learn an etude, a transcription or even know a ii-V line well, may take months of consistent practice.
Stay focused and in the moment with whatever specific task you have laid out for yourself, and most important, do not let overwhelm take hold.