You may want to dowload singing lessons so you can improve your singing a lot.  There are a lot of vocal tutorials on DVD or CD, which can be downloaded to some kind of mobile device that  you can take while traveling.  I like to go on walks and practice some singing techniques by listening to some lessons on a downloaded course.  In the old days, you had to go find a singing coach who would give you expensive lessons once or twice a week.  That can still be a good way to go, but if you don’t have the money, a transportable singing guide might be more practical.