First I have to give kudos to Kelly over at Psycho Carnival ( It's in my link section to the right ) go check it out it's very twisted and funny as hell.
In our present world were allowed the luxury of trust. We generally don't feel threatened or need to be on guard when dealing with others in our day to day lives. Fast forward to the post apocalypse and it's a different story, where if you’re not on your guard at all times you could be dead. This becomes even more paramount when you encounter other survivors who appear friendly and even offer to help you. So what should you do in the event you encounter other survivors who appear friendly who might not be.
The survivors you encounter might look like normal decent people, they cold even look like your grandparents, regardless always have a weapon on your person and be ready to use it at all times. This weapon you want to keep concealed keeping the upper hand if things get ugly.
2. Sleep with one eye open
If you’re alone and encounter another survivor don't let yourself sleep too soundly as they might use this opportunity to attack. Keep your weapon ready to use in a place where you can grab it quickly such as under your pillow or in your sleeve.
3. Keep them in front not behind
If you’re on the move keep them in front of you as much as possible, especially later on in the day if you’re walking. You will be more tired as the day passes and your guard may begin to lower. If their behind you they might take this as an opportunity to attack you when you least expect it.
4. Don't fall for what they say
Over time you will start to talk to these other survivors, were social creatures after all and communication is a primary part of that. Just because they might be friendly and easy going they could be using that to lure you in. Think of used car salesmen for example, their trained to communicate a certain way to make the potential buyer feel at ease and more comfortable in buying a car. A really good one may even convince you to buy a car you initially didn't want or was more then what you were willing to pay at first. The same applies in the post apocalypse, a really smooth talker can easily wear your guard down. You may start to think their alright and befriend them, and that is when they strike.
5. Go with your gut
If all else fails go with your instincts. Even if they seem okay and are friendly and offer to help you with whatever you need, if your instincts are telling you not to trust them believe your gut. Nine times out of ten your gut won't lie.
Remember the post apocalypse will be a desperate world; be on your toes at all times.