Hey Kiung.
Some techniques:
Firstly, get your tradition skills down-pat, like Syndicate said. I'm kinda in the same boat at you, about a year on, still learning
The first thing that will make your paintings look great and stand out, is to be able to draw in a traditional medium, be that pencil, chacoal, or paint. Get a mate to model, or if ya got the money, go to a life drawing class. Sit in the city and draw buildings and streets to get perspective, learn about proportions and foreshortening etc etc.
Also, experiment with colour, pastels, watercolour and inks are great for this. Do some quick sketches, and chuck some colour on them, learn what works, what emotions different colour combinations create.
And while you're doing all this, if you're set on being a digital artist, get to grips with your program.
Find tutorials, videos and stuff, all over the internet. Spend time creating small pieces, pieces that are driven to experiment and learn, not pieces of art. Gradually these will become art.
Also, if you haven't got one already, get Wacom tablet! Though that may be obvious 
Hope this is helpful!
I'm still learning as well, and could give you some links and stuff if ya want.
I'll PM you this as well and you can contact me if you want 
-FF
"I try to make everyone's day a little bit more surreal" - Calvin - Calvin & Hobbes
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