Understand what you are doing
Photography is a skill. Despite digital cameras coming along and making photography easier for everyone out there, it is still very easy to distinguish between the people who understand what they are doing and those who don't. Read the manual that came with your camera (what do you mean “There was a manual!”?) and try out all the different settings and options so you know what each one does. Then take plenty of photos and learn why various things work and others don’t.  

Stay Enthusiastic  
One of the best ways to improve yourself as a photographer is to be enthusiastic about what you are doing, if you aren’t you might as well pack the camera away and go home. Photography has the knack of being frustrating at the best of times especially when it isn’t going right for you, for example, it’s raining on the day you’ve planned a trip out or if you can’t get a smile from that kid no matter what you try. Try to change this frustration into a strength and see it as a challenge rather than a barrier. If it’s raining try some still life shots indoors or better still, go put and put a carrier bag over you camera with the lens poking out of a hole. If the worst comes to the worst give yourself a break and come back to it a little later.  

Talk and read, then talk and read some more  
The best photographers are constantly trying to improve their knowledge of photography. Be it talking to fellow photographers or reading websites, articles, magazines or anything else related to photography, you will learn what techniques are the newest and most effective and also learn from others how to improve your photography. Talking to others about different techniques or experiences will dramatically improve your photography. Use online photography forums and websites and meet and talk with other photographers. Also comment on and constructively criticise other photographers work. The likelihood is that they will do the same for you. Give it a try, believe me, it works.  

Try something different or new  
A lot of photographers take the attitude that if something works then don’t change it. Although that may be the case, I find that not changing or evolving yourself and your work by using different techniques or new equipment/technology you quickly become stale and bored. So, if you think a new piece of equipment would be worthwhile buying or trying a new style might be fun, then go for it (but don't bankrupt yourself obviously!). 

Take more photographs  
It might sound a little obvious but the best way to easily improve your photography is to take photographs. The more you take the better you will get. Therefore get out there and take photos. Once you have, show them to people who will give you an honest appraisal and learn from what they have said. Then get back out and take some more.