If you plan on staying in this field for a while my biggest piece of advice for you is aim for either an in-house job, government contracting, or government security. If I had to rank most likely to be career worthy it would be.
1) Government Contracting
2) In-House Security
3) Government Security
First you're going to have to be in the industry for a few years to build up the experience that a lot of places want. Some get lucky and either though dumb luck or connections get these jobs quickly.
Each job has it's own list of goods and bads
Government contracting is good because they tend to have better pay. I've seen pay scales from 13-40 dollars an hour depending on who the contract is with. Plus contracting for government agencies can help you build connections if they have spots available working directly for the agency. Downside is that you get the same benefits as the warm body guards.
In-House Security is good because it again tends to pay better than you average security job. You get the benefits of the company which a lot of these companies have good benefits. Plus you tend to get treated better since you're an employee and not a contractor. Downside is because these jobs are so sought after they tend to not accept laziness, incompetence, or to be fair you piss off the wrong person and they will dump you quick.
Government security is probably the best because almost all the same reasons. Better pay and benefits. Plus a lot of these agencies provide all the equipment or most of the equipment to their guards. The biggest reason it is the best is because you're a government employee and so you can usually pay into the state pension system. So there is a possibe retirement in it for you if you become vested. Downside is these jobs are very rare and very competitive and they can get political because of their governmental nature.
Hope this helps as a guide for you.