An old habit I have from many years of driving a stick is to shift into 2nd before I go to reverse. Just a quick drop in and then out and over to reverse usually lines things up so it will fall right in. With transmissions that have reverse on the right side I do 1st then reverse. Just seems to line the gears up more closely so that reverse can just slide in (reverse is usually a straight cut gear instead of angled like the rest of the gears).