Two home invasions in one week in my town, how do you protect your self ?

[agentS]

192. Layers of protection

The more 'stuff' you have in the 'way' of an 'invader', the more time you have to notice an 'attack' and react to it in some fashion (ie. calling the police, getting a gun/weapon ready, or hiding in a bathroom/closet.
Having a gun wouldn't have helped the people who got robbed in the OP's post, unless they had it in their hands at the moment the door opened. Having a loaded weapon on you at all times is a recipe for disaster, and robbers are certainly not going to wait for you to run to your gun locker, unlock your gun, load your gun, clear any jams, check the sights, and run back to the living room for the eventual standoff.

A high fence and some security company stickers may be a good deterrent. Dogs and motion sensor lights would help as well. Noisy creaky staircases are useful detectors as well. Deadbolts will slow an attacker down, or at least choose a noisier means of egress. Interior deadbolts will buy you time to shimmy out a window or call the police or arm yourself with a weapon. A hidden wall safe or other hideaway will keep your most important documents out of their hands, unless they're tipped off to the location of the safe or your computer passwords- in which case you're up against pros or spies and you might want to consider more, shall we say robust means of personal security, depending on the expected threat level and the value of your guarded material. In other words, booby traps, off-site storage, escape tunnels, and self-destruct devices.

The key here is to
1) make the robbers think twice before considering robbing you. If they think it will be too difficult, they won't attack, unless you have something THEY really want or you ARE what they want- in which case they're not robbers but assassins or hate-mongers. Dealing with those guys is different than dealing with robbers.
2) Make the robbers work hard to get in. If you can do things to your properly to make unannounced entry difficult, then they won't be able to breach your house without you noticing. That's your ultimate goal- buying yourself time to scare them off, to escape, or to engage the enemy.
3) make the robbers unable to harm you, either thru hiding or using weapons. The weapons don't have to be guns, but keep in mind they dynamics of your house and your neighborhood (and what your ultimate goal here is). An AR-15 is a pretty lightweight weapon, but its long barrel will be disadvantageous in a hallway battle. A shotgun is pretty good, but you run into recoil issues and if you miss your wall repair bill will be higher. Swords and such can be effective, as household battles tend to be close range affairs but you'd better get a good quality one or it will break before you even hit your opponent. LENGTH is also an issue- a bat or sword will be limited by hallway 'airspace', limiting your ability to swing. Unarmed methods of combat will certainly surprise them but without experience you'll wind up being beaten up, or too winded to run- dependent on age or physical condition. There are other, smaller weapons to consider like pepper spray, mace (these can be a bit rough on the nose in close quarters though), tasers, meteor hammers (if you choose to engage the battle in a spacious front yard or have a good pitching arm), or ton Fas/nun chucks. Keep guns/non gun weapons out of the reach of kids, of course.
4) make the police aware that you are under attack. If the home invaders hear you shout out "I've called the cops!" they may bolt rather than find out you've actually called them or not- unless they're pros and know the local expected police response time, in which case fall back to step 3 and prepare for a dangerous battle.

One thing to consider if you think about purchasing a firearm.
http://www.americanrifleman.org/articles/best-gun-for-home-defense/

Gun buyers should be looking for a firearm and ammunition combination offering an optimum level of stopping power. Overpowered guns produce excessive amounts of recoil, noise and muzzle flash that can leave the home defender deaf, blind and pointed in the wrong direction. More importantly, hot rounds are more likely to pass through the intended target, travel through thin wall or window materials and keep on going to cause unintended damage to others. At the other end of the spectrum, underpowered guns will not stop the threat effectively.

Guns are loud, mmkay. That's why I am not in favor of a gun for the only means of self-defense in a robbery. Imagine if the other guys have guns- it's a mess on your senses.
The writer of the article above discounts the .22, but any gun, even a snub nose .22 revolver, will scare off most robbers, unless they're armed themselves or crazy- in which case your calculus changes and you have a different playbook to draw from.