Ok, I don't have any problems smoothing round cakes, it's the square and retangular that I can't see to get. The corners, are impossible for me and the top looks like it has little gullys....

Any advise or technique you can share with me.

Thanks alot.

There are two articles here that might help you out:

How to frost a square cake: http://www.cakecentral.com/article51-How-To-Frost-a-Square-Cake.html

and the Upside-Down Method: http://www.cakecentral.com/article6-Upside-Down-Icing-Technique-for-Perfectly-Smooth-Icing.html

HTH

HEre's some pics on how I do my corners.
http://www.cakecentral.com/cake-decorating-ftopicp-5396443-.html#5396443