Good security cameras are expensive, and they only help you AFTER the fact IF you can recognize someone. Most you'll just know someone was there and that's it. An alarm system is generally cheaper and more effective.
there are wireless motion, glass break, and windows/door sensors that can be used without doing wiring, although wired is better. They work with a central panel and can be monitored or unmonitored. Just having them set off an alarm will usually make people run.
There are also standalone products like these.
www.newegg.com/Product/Product.aspx?Item=N82E16881147008
They are cheap and really only effective if you're home to hear them go off, but will certainly wake you up if there's someone breaking in. Again just the sound can make them run too.
There's also landscaping you can do (thorny rose bush under the windows) and motion activated flood lights will discourage people as well, as they don't want passing cars to see them sneaking around.
Changing the locks an bolts won't do ANYTHING unless they used a key to get in... And they are very easy to pick/bump without a key anyway if it's a theif with half a brain. thankfully most are stupid and easy to scare off, simply because with a little effort there will be lots of easier targets than you.