Every true coffee lover will have their very own method of creating the perfect espresso, the technique is a very personal thing. Here's my favorite method. The most important part of any coffee is the water, if the water is of poor quality then any drink you are going to make will be awful. Even if you use high quality coffee mixed with dishwater it's hardly going to taste very nice. The water must be fresh and very hot. You should not use water which has been standing for some time as it can taste a little stale.
You must clean your kettle or coffee maker, even if you are just making one cup. Make sure the water is filtered. The ideal temperature for making coffee is 95C which is almost at boiling point. The next important part is the coffee, I like to use Arabica coffee beans. I'm not really that picky where they come from as long as they are grown above 3000 feet and are freshly brought. You should roast them yourself if possible or if you buy roasted beans then make sure you get them as fresh as possible.
Robusta is a type of coffee which is very easy to get hold of, it's resistant to diseases but it contains fewer flavors and more caffeine. This variety is not really suitable for espressos, it's just for a simple cup. I like to grind my own coffee using a burr, I'd steer clear of the blade grinders.
You should ideally use French or Viennese roasted beans which are quite dark in color. The blade grinders chop the beans rather than grinding them. The burr type of grinder use rotating pyramids to grind the coffee. The gap between the two plates will determine the size of the coffee granules which you produce. A good sized granule is in between the size of a grain of sand and smaller than a piece of gravel. You should not leave the ground coffee exposed to the air for longer than absolutely necessary, Coffee will lose flavor if exposed to air for a long time.
You will also need a high quality espresso machine in good working order. Make sure you take good care of the machine and clean it on a regular basis. You need a good machine which produces high pressure of a minimum of 9 bars. You should also choose one that heats water with a boiler or thermo block. A thermo block is environmentally friendly as it heats the specific amount of water required as it travels through the machine.
Cheaper machines will create the pressure by using steam which should be avoided where possible. Now you have everything you need what should you do? Start by heating the machine by running clean water through your machine. Turn the machine on and let the water heat up, then run a cup of pure water through to flush out the system and clean it out.
Add your ground roast to the machine, pat it down a little as if you were putting tobacco into a pipe. The coffee should be packed neatly into the machine but there should still be some springiness. Put the warmed cup where the coffee will come out and press the button to start the machine working. In around five to ten seconds you should have a stream of coffee. If you're making a cappuccino then you should warm half a cup of milk in your microwave and then froth this up and add it to the espresso.
Focusing on the topic of one shot coffee makers, Jack Blacksmith writes most often for http://www.coffee-espresso-maker-tips.com . You can have a look at his articles on one cup coffee makers on his site.