Brushing Overview?

I haven't visited here in a while. I have been browsing around lately since I have been wanting to get back on my optimal health quest. I have learned so much from you guys it's insane.

But aside from diet stuff... I use a massager and boar brush on my head but not consistently. I have read that some of you really swear by it. How long do you brush and how frequent? If I do it too hard and for to long my head will feel irritated the next morning if I try to brush again. I will say it def does feel like it brings a ton of blood or something to your scalp.

I've even read on some eastern medicine sites that dry brushing your body stimulates immune system activity. Any links or info on how I should be doing this would be much appreciated.

Peace fellas!