I practice a ton.  But a lot less than I used to.  When I was playing college golf and I wanted to feel like I was really getting better, I'd bang a couple hundred balls a day, usually with a club on the ground, telling myself (and anyone who would listen) that I was trying to groove a particular portion of my swing.

I was kidding myself.  While there is some value in working on a particular movement or issue with your swing, make sure you do it in moderation.  You can get really good at re-creating that particular movement on the range, that afternoon, using your 6-iron, but if you do it for more than 15 minutes, you're only grooving that moment to that moment.  When you try to blend that movement into a different setting or club (like taking it to the course) you will either go back to how you were doing it before or a rigid, mechanical version of your old swing that gets you nowhere.  Even if you feel like you do it well enough for a hole or two, that feeling you "grooved" on the range is not likely to stick.

The tip above in the video can help blend swing changes or particular points of emphasis from the range to the golf course.  Work on a part of your swing with a drill or a feeling you're trying to integrate into your game for about 10-20 minutes, tops.  Take a quick break.  Grab a drink of water.  Then go back and hit about 10 warmup shots, hopefully not thinking too much about the specific movements that you were working on.  If you hit all 10 awful, ok, go back and work for another 10 minutes.  But if it feels ok, try the drill I describe in the video.

Really try to imagine the course you play on regularly.  Picture the group you usually play with.  Try to conjure up that butterfly you might feel on the first tee, even if it's just so you don't top it in front of your league.  Taste the adult beverage of your choice you might drink.  Smell the nasty stogie someone always smokes.  Now picture the fairway from your first hole on the range between two flags, or a house in the distance.    Now try to hit that first tee shot down the middle.  I promise you that if you give it a reasonable effort, you won't feel exactly like you're on the course, but you won't feel like you're at the range either.  It's a strange middle ground, and it's exactly the feelings you need to help simulate what happens from the range to the first tee.  Play a few holes that way.  You probably won't have the patience for all 9 or 18 at first, but you'll be amazed at the difference in focus you feel when you do this.

You can go back to working on your mechanics after some holes, but use this visualization drill to help blend your mechanical skills into the course setting.  Additionally, next time you're up on that tee shot that makes you nervous, you've already hit that exact one a number of times before.  You'll be amazed the confidence it will give you.