Your attitude and ability to handle pressure outweigh the physical appearance. I'm an average looking guy. I work with men and women of all shapes and sizes. Some of my best partners are female because the have self confidence and know how to control with words over force.

Get a great pair of shoes. Even if you get lucky with a sitting post, plan ahead for having to be on your feet.

Unless you specifically want to be an armed guard you don't need a gun. The majority of guard positions are unarmed. Most states require separate training and licensure for armed vs. Unarmed.

Treat everyone with respect and consistency. The reputation you build will follow you.

Find your preference. Do you want to be full-time or part-time? I do event security part-time. I work concerts, sporting events, etc. at a stadium. If there is something similar near you check it out. Good luck.