...look where you are going, don't get too worried if things are slightly slidey.
+1
Grandparents have a long gravel driveway that has 2 pretty steep hills and deep gravel. I was so tense the first few times I rode on it, I had to dig the seat cushion outta my ass with a crowbar. I eventually learned to deal with it, now it's nothing.
...relax, loosen your grip. Let the front tire track a little. Don't force it, it's ok.
...I use the rear brake only. Not taking a chance. But that's just me.
...look where you want to go. It's amazing how many situations this will get you out of. It's almost like the bike is hardwired to your brain. It has saved my ass more than once.