Help!! How can I practice Beethoven's first concerto in c major?

Isolate the trouble spots and use them as warm-ups that are practiced with repetitiveness on a daily basis. Practice them slowly and increase the tempo as you gain fluency with the passage. Once you have mastered a particular trouble spot, put it in its context within the composition. There is no need to continually practice those sections that give you no problems. As you mature in your playing, you will look back and wonder why a particular passage ever gave you a problem.