Hiya and welcome! A "geezer" bike huh? Hey at least you're riding a bike!!! Good for you...

OK...Surly is dead on... always carry an ID, a phone, a little cash (for a call or food if you suddenly need some carbs, often called "bonking"), pepper spray (for dogs, animals AND creepy people!)... and definitely let someone know where you are going and about what time to expect you back! And always, always wear your helmet! Even a slow speed crash can result in an injury... a helmet is pretty cheap health insurance.

as to increasing your miles, ride as far as you can and enjoy! If you feel good, ride! If you're feeling like your legs are wood, take a night off!

Try to carry some carb packs with you as you increase your distance... if you begin riding more than about 25 miles you will want to take in some carbs so you DON'T bonk... lots of info here about women and fueling for riding!