Making a plastic awl out of a scrap piece of poly works well lubed with the chap stick as mentioned. Take the poly awl out and folow with the gut tip.
Also , once you cut the tip of the gut to a sharp point, you can use some super glue to the tip, only a small amount, then spray it with super glue accelerator and that will set it up immediately. Now the tip is stiff to push it through.
I string a lot of nat. gut, and usually all is needed is to cut a well flattened tip of the gut to a sharp point is all that is needed, and push in small increments.Flatten that tip with your starting clamp before you cut to a sharp angle.With a razor blade you can cut a very sharp angled point. It may take a little time, but will save time in the end.
Once in a great while I resort to the poly awl technique, but the above works 90+ % of the time .