For a size ten hook three strands is fine, & four will be just slightly bigger. It's really personal preference of the look you're trying to achieve. As far as separating those strands pinch one end of whatever length you want in your vise and spin a little to unwind them a touch, while holding the free end insert a bodkin at the end that's in the vise and separate out how ever many strands you want. You didn't mention if you did an underbody or not to taper the abdomen to the thorax, it's important to get that as smooth as you can so you'll end up with a nice clean body when you weave. Low areas will show after you weave the fly. As you start the weave you must try to keep the same tension throughout the process, pay attention to where your overlap points are on both sides and keep them the same ie: in the middle of the hook, near the bottom, closer to the top how ever you choose to do it. As you overlap the the floss you must keep the piece being overlapped in the same position straight out from the hook and don't let it move up or down, or front to back until you get the traveling piece to the other side and in position this will lock in your overlap point and you can then do your next one. Keep in mind you must keep the same tension throughout and not let the standing piece move until the travelling piece locks it in place, this will keep your overlap point in line. Don't worry about what or how your weave comes out right now, all your doing is getting the process down right now. You must pay attention to what and how things are going while your getting the technique down, ( that way when a few points line up you'll know how you did it and when they're up or down to far you'll know why) you'll see how your overlap points start to line up little by little. When you get to the point on the hook where you're ready to tie off have your bobbin ready with enough thread out of the end that you can trap down the material you're weaving with. You hold the strands straight up on the hook and start the thread on in front of it then trap it down. The more slippery the material you use the harder it is to keep the overlap points in line until you get a handle on this, chenille is a great one to use for practicing at first. The main thing is while practicing this is when you feel yourself getting too frustrated put it down and come back later. It just gets worse if your head is in the wrong place. If this isn't clear enough let me know. It's kinda difficult to run through this and get everything. Hope this helps.
