Some resources for Hindi keyboards
On the PC - Google Hindi input. With only two keyboards enabled (English and Hindi) switching becomes easier using Alt+Shift. There is a learning curve in this transliteration based input too, but after some time it becomes second nature, though not as fast as typing in English.
On Android - 1. Google Hindi Input 2. MultiLing keyboard
On iOS - You can use the inbuilt Apple keyboard. The layout is quite logical and auto correct speeds up things.