Maxout,
I sympathise with you totally on this one. I found it impossible until i found an instructor who gave me some advice that worked for me.
The other posts have covered the important stuff and it sounds like relaxing would probably be the best thing to do. I remember finding this very hard to do at £7/minute.
The piece of advice that stuck with me is 'Scan like a b****'. The moment the ILS GS needle moves up a fraction apply one degree nose up and hold it and scan until it moves again (and it will). Other than that trimming and don't correct a turn outside the heading bug on finals. Its all down to practice really.
Good Luck.Don't give up.