Leaking tappet/cam cover gasket

My name is Roger and I am from South Africa,I own a 2006 Chev Aveo 1.5 Ls.The car has given me good service and is both reliable and fuel efficient.I do however have a persistent problem with the tappet cover gasket.I have replaced this item 4 times within the last 2 years as oil leaks through the gasket.It is more of an annoyance than anything else because the engine bay becomes dirty and oil leaks onto the driveway.I also have to top up oil more often than normal.I make sure I don't tighten the bolts too hard so as not to break or distort the gasket but the problem persists.I was thinking of making my own gasket as the current one used in the Aveo is really thin.Has anybody else had this problem?If so what advice do you suggest?Any help would be appreciated.Thanks