For portable cleanups after field service or the junkyard, use Costco Baby Wipes. Nice pop up container, fairly tough fabric. Does a nice job, you'll be surprised. I have to have presentable clean fingernails at work and if you work a baby wipe under the nail it gets squeaky clean. And you can have a pack of 'em in your truck, many uses....
At home, if soap won't do it, I'll rub a teaspoon or so of cooking oil (usually extra virgin olive oil, fancy, eh?) into my hand and work it into the grease stains, loosens them right up, then soap and water. Doesn't tear up the hands the way the more aggressive cleaners do.