Beginner & want advice please

The first thing I notice is your brush opacity.
Stacking that many transparent brush strokes improperly makes it somewhat noisy and not readable.

Study stroke economy, bigger and more confident strokes might do you well.

If you want an example of the same 'style' executed better,
see Camila Vielmond's work.

i.e. http://orig03.deviantart.net/78ce/f/2014/261/9/7/97259fd461956654890c17d866afa753-d7zot0y.jpg

Her right hand that's holding the sword is missing some details. Just general creases that should form around her fist. Also her head seems a bit too large and the neck seems a little thin. However keeping it as the way it is, adds some style to the painting so I wouldn't worry about it.

First of all I'd like to say I really like it stylistically. The colours and brush strokes grab my attention, and the body proportions are close enough that the thin neck and long arms feel like a choice rather than a mistake.

What I'd critique is the heavy focus of light around the character's midsection. Although that's the exit through the trees I assume behind her, the heavy contrast between her dark dress and the bright light draws my eyes away from her face, which is much more interesting to look at than the chest.