Its really important with highly reflexed ELB, to exercise the limbs thoroughly before trying to string. Like Badger has mentioned low brace height is not good, as the bow sometimes wants to twist. I usually exercise it with a loose string, on a tillering tree holding the bow on the balance point/ rest so it won't turn/flip. Slowly stretch the limbs, work out any gross imbalance in limb strength and hinges, then exercise to brace height.
Now the bow can usually be strung safely. Despite taking all these precautions, sometimes you still get limb twist and string alignment issues(esp on narrow bows). Check the unstrung bow to see if the centreline was laid out straight, or if the stave has taken some sideways set. A combination of simultaneously slowly drawing the braced bow the opposite direction of the list and back can help correct the problem(providing you have gotten it to a decent tiller in all other aspects besides twisting /listing). Usually the bow will start to correct providing the limbs were evenly reduced into a balanced arch on the belly. You are essentially training the twist out of the bow before pulling it too far and getting a sideways set.
If you haven't done an even job, either with the layout, or with the cross section of the belly along the length you will need to reduce wood on the opposite side of the twist along the limb/limbs. Keep exercising the bow frequently.
Initial layout, and limb design can minimise a bows susceptibility to twist. Narrow bows that taper directly from the handle to the tips in a straight, pyramidal line are more likely to twist. This can be avoided by leaving the first 4-6" as wide as the handle, then taper to say 3/4", at 6-8" from the tips, then down to 1/2" or 3/8" at the tip.
