It depends on what technique the person doing your hair uses. Some braid it first - this is a strong hold, but I don't think it looks as natural. Another way is to twist them in, this is difficult to master and does not seem as secure as braids but last just as long if done right, and looks fantastick very Natural! I know a shop owner in Brooklyn that twist them in, she also holds classes on how to do this technique. I kept mine for almost 6 months with two tochups.
I've used both human hair for kinky twist which is extremely expensive - the human hair is softer and less damaging to me. The synthetic looks just as good as the human but can be stiff at first which can cause some breakage if not handled with care. HTH
I forgot to add, I've always had a relaxer when I've got my hair twisted, but I do wait as much as 5 weeks or more after the relaxer to give hair strength
