Never clean these tools with solvent and air pressure. This can drive small particles of dirt into the tools. The parts you are measuring should also be clean. Measuring tools should always be held with both hands because dropping them even once will probably necessitate either factory repairs or recalibration. If you need to use a magnifying glass to read the fine markings, use the type which you can wear like glasses to leave both hands free.
Proper feel is essential to the accurate use of precision measuring tools.
Practice with calipers and mikes on gauge blocks or other objects of known dimensions until you arrive at the correct measurement every time. If you set your tool to the desired measurement and then force it onto the part, you can damage both the tool and the part being measured.