Well, I started submitting my arts into groups when I joined DeviantART (thru the help of my senior who invited me to join deviantART). I've participated in some community contests and challenges too..  I met a lot of new friends from all around the world in the forum chat room, we exchanged opinons, ideas and even techniques.  I got a lot of new watchers after my first Daily Deviation..  people eventually suggest my art to be included in groups and this gave me more exposure..

And I do check out all the deviant artists which are on my watch list on a weekly basis. 
I've been inactive in deviantART for a few months already.. (Lesser interaction with my watchers  , didn't manage to reply all the comments on my profile and art.. accumulated more than 1k feedback messages.. )

In a nutshell, the best way to promote your art in deviantART is by joining groups and take part in more community/ DeviantART contest.. Good luck!! 

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Added on July 13, 2012, 10:00 pm
Well I see.. I'm not really good in commercial design..    especially when I need to design based on the client's taste instead of my own ideas and execution style.

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Added on July 13, 2012, 10:09 pmanyway, got myself a tablet finally.. a tablet WHICH BELONGS TO me.. TT_TT wacom bamboo pen&touch small.. I'm not sure whether I should continue to do more matte paintings/manips in the future or move on to Digital Painting.

this is my first try at painting a landscape.. a quick one, haven't finish this tho

So much fail compared to what I can do by using matte painting method