My 2 cents...
Don't waste your time with artificial sinew except maybe just to learn with. You still have to knot it and it starts fraying and getting nasty after a few dozen shots. I've tried coating the wraps with super glue, but that doesn't last either.
If you don't have sinew, cotton thread works pretty good, small enough thread that you can keep the wrap smooth, and then a thin coat of super glue over top to finish. It will be tough and waterproof.
Real sinew is the best in my opinion. You can waterproof it with super glue or better yet a varnish made with pine pitch and alcohol. This will be a really strong attachment and holds up great to a lot of shooting.
If you don't have your own sinew from deer or otherwise, I've been able to get some from etsy, but it's become pretty expensive. Best bet is to get it from someone who hunts, or I've heard that processing places will hook you up if you don't mind doing the dirty work of cutting the leg sinew out.
Best of luck with your arrow building. This place is great, I've learned a ton from reading through the old posts, too.