To prevent your phone screen from accumulating dirt, you can use a screen protector. These stick to the screen to protect it against dirt.
Change the protector when necessary and wipe the screen to remove any remaining dust particles.
Screen protectors can also be useful to prevent your screen smashing if you accidentally drop it!
Always keep your phone turned off while cleaning.
Use soft cloth (microfibre is preferable) while cleaning your Smartphones. Do not use tissues or paper towels, as they contain abrasive particles that may scratch surfaces.
Use distilled water in a spray container. For a stronger effect, mix this half-and-half with vinegar and clear it with soft cloth.