How to...paint (easy) birch trees

You wouldn't believe it, my eldest struggling with possible early stages of appendicitis, my husband diagnosed with bronchitis and my youngest battling the flu...and on her 13th birthday of all things.  Yikes!  This is been a tough autumn so far.  And, at the same time, I've been avoiding doing the work I need to do.  Instead I painted a small grove of birch trees for my daughter who will be home from University in 3 1/2 weeks (yes!).  I've been considering painting her room for awhile but really, really like the grey-blue walls (a favorite colour of mine) so, inspired by the bare trees outside I decided to paint birch trees instead.

TOOLS:
1-4 inch foam brush
1-3 inch foam brush
1-1 inch foam brush
1-1/2 inch flat watercolour brush
1 tester sized can of white acrylic paint
1 small craft bottle of navy acrylic paint
1 photo for reference
And a grey-blue painted wall (the background was painted a few years ago mixing leftover house paint)

Looking at a photo I took of a grove of birch trees, I decided to focus on the trunks and leave out any branches as I wanted this to look simple and a bit contemporary (because that's my girl).  I decided to create trees using all three sizes of foam brushes in random order and added a few larger trees by using the 4 inch foam brush in two stripes.  I also decided to leave the white at the first coat as I liked the rustic effect of shadows caused by the base paint showing through in spots.  This is the fun part because

a) the lines definitely DO NOT have to be straight
b) there is ABSOLUTELY NO measuring involved
c) and there is NO NEED to draw first

Once the white paint dried, I added knots and dots and lines using the watercolour brush and navy craft paint.  Again, I used my photo as a loose reference but wasn't looking for perfection.  And, VOILA, a fresh, new look in two hours :)  Now that's my kind of redecorating!

P.S.  OPTION: add small white and branches & navy birds (which I may do at some point but I like it like this).