Um, I‘m no expert but ... (sigh ... I‘ve got this compulsion to state the obvious ...)
Okay - in the photo‘s of D-n-A‘s scrim, he used a CADPAT background - did anybody else notice that his helmet literally stands out like a sore thumb ... ? The CADPAT colours and pattern are both the result of years of good, solid, scientific research.
When I added my scrim, I cut up some non-reflective materials in colours similar to the CADPAT colours and added them on in roughly the same location as the corresponding colour on the helmet cover ... in effect, extending the CADPAT theme to the scrim
(and, yes - I add vegetation when it‘s appropriate, and I incorporate my moustache into my face cam ... which is why it always looks like I‘ve got a branch tattoo‘d across my mug) - I‘ve also got a small bag of extra pieces in colours like brown, for when I need them (i.e. the old helmet cover was reversable, green/brown - the new CADPAT cover doesn‘t have that option, unless you‘re issued the arid pattern in which case you‘d change the whole kit and kaboodle).
I‘ll get out my digicam and take some pix ... when I‘m REALLY bored.
The other tips were good - emulating a ghillie suit, and breaking up the silhouette by having some pieces hanging down below the bottom of the helmet ... as long as they don‘t interfere with your peripheral vision or get tangled up in radio handsets, etc. - one simple way of achieving this is to have some pieces hanging down at the back of your helmet, disrupting your silhouette from the "front on" view - also, adding extra to the sides, or better still just one side, but NOT the top will change the shape of your gourd ... which is the point in the first place (I‘ve got a photo of some Italian troops somewhere - they‘ve imitated the black feathers on their headdress in their scrim, and it‘s kinda neat).
However, it‘s fairly difficult to go through all of this via the Net - you‘ll catch on when you see good cam and scrim in the field, and your section commanders will be much better coachs.
But, like I said - I‘m not the ultimate authority, but ... I‘ve got friends who are.
P.S. (we were ordered to remove our scrim when we went to Afghanistan, but here‘s an old photo "pre-CADPAT" - at least it illustrates the attempt to break up the silhouette ...)
Ooops - didn‘t cam up my teeth ... or my ears ... for shame!