First, you have to develop your manual and pedal technique. What this means is that your fingers have to be able to play anything you command to them. The best way to develop your finger technique is to play manual scales, arpeggios, chords, and special exercises regularly.
For developing a pedal technique playing pedal scales and arpeggios in all 24 keys works wonderfully. Take a pair of one major and minor key with the same number of accidentals and play a scale and arpeggio over one or two octaves. Do this every day for 15 minutes.
In order to become a competent organist you also have to develop your hand and feet independence. You see, even if all your fingers might be able to play anything you want and your feet can play even the most incredibly difficult passage of pedal lines, you still have to be able to play hands and feet together.
As you know, most of the time in organ music hands and pedals play different melodies. Therefore, your hand and feet independence has to be developed to a level when you could play anything with your hands and feet together.
The next thing you have to do is to develop a wide variety of repertoire. Try to learn new pieces every month. Your organ repertoire should be varied enough and should include organ compositions from many different national organ schools and historical periods.
For example, you should not limit yourself to the well-known organ works of Bach, Buxtehude, Couperin, Franck, Widor or Vierne but also try to learn and master pieces from lesser known organ schools like Spanish or German Renaissance, Italian Baroque or even compositions from the Middle Ages.
Also remember that you have to learn the foundations of music theory which will allow you to better understand your organ pieces you are playing. Learning basics of harmony, counterpoint, and fugue would be also beneficial. Finally, try your hand at organ improvisation - this will give you much joy from your increased creativity.
Apply my tips in your practice and with time you will become a competent organist. But remember you have to be consistent and systematic with your practice, persistent with your efforts, and never give up on achieving your goal.