Always, always use screen cleaner wipes on the screens of smart phones and tablets/iPads.
The wipes above are designed not to remove coatings that are applied by the manufacturers and are not abrasive.
I am telling you this because I saw somebody use a paper napkin in a Tim Horton’s coffee and doughnut stop. Paper napkins and kitchen roll are not refined enough to be used for cleaning, and contain very small wood chips which over time will degrade your screen.
Kleenex style tissues are also not suitable, especially the type that contain Lanolin or other products which make them appear silky smooth. This type will ADD layers to your screen.
You don’t have to carry the whole tub. Just put a couple of wipes in a small Zip-Loc sandwich bag.