How do I keep dirt out of my nails?

Wash your hands with dish soap. Use dish soaps to clean your hands and nails. ...

Use job-specific hand soap. Consider purchasing a cleaner specifically made to remove grease and dirt from the hands. ...

Use a washcloth. ...

Run lukewarm water. ...

Use an orange stick.

A mix of showering regularly, washing your hands regularly and using a nail brush should minimize the issue. 

Wash your hands often.

clean it every day . use warm water for cleaning 

Stay away from dirt.

U cant                

1. Wear hand protection, like gloves, to do dirty jobs. Or even not so dirty jobs. It's old fashioned but not incorrect to don the white gloves when you leave the house. And it allows you to gracefully deal with any messes life might hand you. 

2. Keep them cut short and wash your hands frequently, scrubbing under your hands with a brush and/or cleaning under your nails with a wooden "orange" stick. Yeah, use a nail file tip, tooth pick, whatever if you must. Better than dirty nails.

3. Daily shampoos that also clean your nails. If you don't shampoo that often, then a 3 minute soak in warm soapy water followed by a scrub and nail cleaning. 

That daily soak might sound like a lot, but think about what kinds of awful stuff your hands may encounter as you go about your daily activities! It's not like you can't talk on the phone, watch TV or something while your nails soak! 

I save old food containers - like cottage cheese - a separate container with lid for each size keeps them clean and rust free.

OH . . . . . FINGERnails ! . . . . . . why didn't you say so?

Wear gloves.                

You can keep dirt out of your nails by always wearing gloves. Constantly. At all times.