There are four things the modern gentleman should be able to do: change a tyre, tie a bow tie, start a fire and, most importantly, mix a great cocktail. You may feel that the latter is probably the most difficult to achieve, but with a little practise and a lot more confidence - this could prove to be a valuable and impressive tool.
There are many classic cocktails you could choose from to be part of your repertoire (see below for my favourite) but for maximum effect you need to make a bespoke creation that reflects whoever you're trying to impress. Learn your guest's favourite fruits, herbs, juices and spirits and get to work on a cocktail that you can name after her. This will show that you are a great listener, and ensures your bar at home is the only venue that will serve her favourite cocktail.
SOME COMMON MISTAKES
Make sure you get the correct balance of sweet versus sour. If you get this right, the cocktail should taste like a sorbet. If anything, make it more on the sweet side as it is generally more palatable than a sour drink.
When using egg white in a drink, this is only for aesthetics and texture. If you can taste it then you have used too much - it will be chalky and unpleasant. Only use approximately 5-10ml per drink.
Never ever buy citrus juice pre-made in a bottle; nothing is fresher and more delicious than freshly squeezed. Also, you can play around with your sour of choice - why not use pink grapefruit instead of lemon or lime?
Strong drinks are lovely if they are made correctly, but generally you can only have the one. A good rule should be that no drink exceeds two units of alcohol, which equates to 50ml of alcohol per drink.
Don't make the garnish too elaborate. The star of the show should always be the drink; the garnish should be simple, rustic and serve a purpose. No cocktail umbrellas and sparklers, please.