From the beginning you should set yourself a goal. Many people learn the ukulele because of a desire to play like their favorite artist (e.g., Tiny Tim or Israel Kamakawiwo’ole), or to play a certain style of music (e.g., Hawaiian songs, Swing, etc.). Motivations such as these will help you to persevere through the more difficult sections of work. As you develop it will be important to adjust and update your goals.
It is important to have a correct approach to practice. You will benefit more from several short practices (e.g., 15-30 minutes per day) than one or two long sessions per week. This is especially so in the early stages, because of the basic nature of the material being studied. In a practice session you should divide your time evenly between the study of new material and the revision of past work. It is a common mistake for semi-advanced students to practice only the pieces they can already play well. Although this is more enjoyable, it is not a very satisfactory method of practice. You should also try to correct mistakes and experiment with new ideas.