I used to do the same thing on campus with herbal cigarettes (since I don't smoke nicotine.) I would empty about half the cig, put some well-broken weed in, and then pack some of the original cigarette content in on top. That might help you, that way it won't smell like weed RIGHT AWAY when you light it, you'll be starting and finishing with the tobacco smell. Maybe even blend your herb with the tob before packing it in.

Otherwise, the axe is a good idea, maybe consider carrying a pack of mints/gum as well for your breath. Any time I'm smoking in secret I like to wash my hands/face right after blazing, which really helps. If you're getting red eye then natural eye drops work wonders, available at any local pharmacy.

Also, why not go for a little walk every time you want to blaze? Just walk around the block smoking the loaded ciggy. If you get paranoid make it a different block each time

Anyway, I hope that helped. I've been stealth smoking on and off for a few years and never got caught in the act. If you've got any more specific issues let me know and I'll try to help!