I'd be inclinded to start with something like a Glenmorangie 10yo. It is a smooth and I suppose creamy dram and I don't believe there is a better introduction to single malt whisky.
You might also want to try a vatted malt e.g. Famous Grouse 10yo or vintage 1992, again a worthy inroduction to malts.
Have a look at the other messages around these boards and you'll soon get some ideas.
Hold on to your Glenfiddich 18 though. As your palate develops you'll soon appreciate the nuances of this dram. It is not a bad drop.
To the novice, all whisky will taste much the same and blends are favoured as they seem more gentle. However, once you discover the subtle differences between single malts you'll be hooked!