How to set a distinctive tone for SMS or phone call from a particular user/ phone #? I find that I'm getting "alert fatigue" and ignore most of them, even thought I've disabled all but SMS and maybe a couple of others.

If I am out doing something like riding my bike/skiing/etc.  I want to ignore all but ones from my wife or kids.

I'm on Motorola Razr-M w/ Android 4.1.2
Open contacts, tap the name of the contact you want to set the distinctive ringtone, then open action overflow menu (the three dots) and tap "Set ringtone", select a ringtone different to default one and tap OK.