I have noticed on a lot of the blood trails about fifty or sixty yards before you find the deer, they start rubbing up against trees every few yards leaving an easy to follow trail. I like seeing that when I am tracking one.

a tip for bloodtrailing in tall grass. as a last resort take a roll of paper towel, or better yet toilet paper and swing a few feet of it through the grass. if there is even a tiny drop of blood there it should pick it up. i say use it as a last resort because you might end up walking in circles or grids trying to find blood this way, and you dont want to walk over any sign.