This is one the most essential tools you could have because it serves so many important functions. Staying in touch with clients, updating social media, storing and accessing information, and working on projects with your favorite design apps are things you have to be able to do anywhere. It also helps to have a camera with you at all times as well as some music to play for relaxation and inspiration. Any serious graphic designer should always keep their smartphone charged and nearby.
Notebook and Pencils
Although today there are many convenient ways to make notes digitally, there is no substitute for old-fashioned pencil and paper. Almost everyone learns or develops some kind of shorthand or personalized system of organizing ideas on paper. This often does not translate well to electronic devices, which certainly have their place, but studies have demonstrated that people retain information better if it is in their own handwriting.
Staying focused can sometimes be a problem no matter where you are. If you live in the city or with other noisy people, then this may be a constant challenge. For some, too much silence can increase the likelihood of getting stuck on a problem and for longer periods of time. A good pair of headphones to listen music from your smartphone is one of the best ways to block out unwanted sounds. The music will not only minimize distractions, it can also reduce fatigue and provide much needed momentum when you need it most.
Stylus and Tablet
These go hand in hand, enough to consider them a single item, and are the means by which much of all design work is done. The necessity to deliver on time and with precision makes a quality stylus and input tablet indispensable to the craft. You should no more be without yours than a musician should be without an audio recorder. Pencil and paper is essential but might not always be sufficient to the needs of the moment. There are plenty of low cost, easy to carry options that will also work with a smartphone.
Carrying Case or Backpack
Staying organized is important no matter where you are. A well-designed backpack, briefcase, or other type of bag is one of the most helpful ways to keep all of your essential tools ordered and easy to find. The ideal one will have plenty of large and small pockets that are sealable and useful for a range of purposes. It will also need to be durable and have a reliable resistance to the elements, so that your work stays protected when you are on the go.