Tablet computers and other mobile devices are widely used in education and other life activities. However, touch screen keyboards are not adapted to languages using alphabets with more letters than the English alphabet has. In this paper, we analyze the existing keyboards on such devices for various languages, influence of keyboard usability on the number of typing errors, and propose keyboard design guidelines for non-English languages. As an example, the layout for the Lithuanian language keyboard (32 native letters and 3 foreign letters) has been presented here. The described solution is not strictly related to the peculiarities of the Lithuanian language alphabet (apart from the number of letters), therefore it is suitable for other languages using a similar number of letters.