I started going to the driving range in september, every friday if possible.
After a few times I noticed that there was some progress, but balls were going left and right, and sometimes straight.
So I figured a few lessons would be needed.
Now I've had 3 lessons and I must say that taking lessons is absolutely a must.
Otherwise you will develop your own personal swing, which will not be as it should be, and afterworths it will be dificult to learn a new better swing.
It's better to start from scratch with lessons.

In my 3 lessons we've covered:
1. grip and position
2. finishing swing
3. backswing

Ball's are going easily 100 meters with a 7 iron and much straighter than before, so YES these lessons helped.
And I will continue with the lessons.

Also don't go hitting balls for 1 hour: take 30 minutes and then take a little break and go on for another 30 minutes.

Only practice when you're having fun: if you start getting angry because thing arent going well, take a break ...