The same rules of hygiene apply everywhere - both at home and on the go. If you need to touch anything after you wash your hands - the door (or the hand rims, if you’re in a wheel chair) - it’s important to use hand-sanitizing gel or wash again. Many people find it helpful to keep needed supplies in a bag. It’s also a good idea to keep extra supplies in the car or at work.
Remember, users performing intermittent self-catheterization should follow the advice of their healthcare provider.