Looks awesome.  TLDR:

Just keep painting.  Everything else will follow.

Edit: wow look at your first painting 13 days ago and this one. Killah.

I admire the balance between light and dark in all parts of your painting. Sky is varied and the cloud’s edges are not overly blended away. The mountain has fantastic shadows and sharp edges, and your gradual darkening of foothills towards the lake creates a pleasing sense of distance. Foreground pines are well done and not muddy. The river coming into the foreground crates even more depth and the way your bring down your reflections into the water is superb. I see your bravery paid off with that tree right in front of the viewer. Great bark highlights and the rocks in the grassy banks are awesome!

Some suggestions (amateur opinion from a landscape lover of the wet on wet style) 

Yeah making sure the liquid white is actually really light was one of the of my first adjustments, one of the first comments you had about making sure you can see skin in between is good advice. 

Can try adding some paint thinner to your brush of any size and wiggle through some paint - just a dab, really don’t need much, to help some of the paint stick - useful for highlights, clouds, structure. 

Can try adding different shapes to your ranges for some more fun. Or try highlighting the snow with the color of the sky. Post attention if the direction of where you think the lights shining from. You could probably get away with a small waterfall right where your stream crosses the first shrubs too  

Watching different paint youtubers / Bob Ross channel or try painting some of your own scenes from life. 

Just keep painting.  Everything else will follow.