Consistency is key for progress. You need to practice regularly and in a very disciplined manner. Start with warm-up and technical exercises before jumping to the fun part of playing a piece or a song. Ideally, if time permits, practice a minimum of 1 to 2 hours per day. A minimum practice of 15min every day is important if you don’t have time for longer practice sessions. Practice every day and don’t wait too long between practice days. Better practice 15min every day, then dedicate one or two days per week for longer practice sessions. Also, always use a metronome, especially if you’re a beginner. I cannot stress enough how important a metronome is. Just use it.
Oud in general is more difficult in the beginning than these two instruments and this is due to the fact that it’s a completely melodic and has no predefined sets or keys like the piano keys or the frets on the guitar. However, that does NOT make the Oud the more difficult instrument to play in the long term. Developing techniques and skills on the Oud should get easier as the time go by, as long as the student follows an academic method and doesn’t develop bad habits that don’t get corrected by a teacher.