Why would I feel the need to tell others?
So you know where to go plunder later? lol
I don't tell others I'm even interested in prepping, My peer group already thinks I'm weird because I do some canning and like to learn about some survival stuff. This would send them right over the edge. And if the shtf they would def be knocking on my door.
I'd buy a deck of cards with thought provoking questions and post them on my regional firearm enthusiasts prepper forum. 
Generally, I go with the old saying that "Loose lips sink ships". I don't talk about what I've got to those who aren't of the same mindset, but sometimes circumstances lend a good time to talk about some things.
Instead of saying that I'm preparing for TEOTWAWKI, I normally talk about being prepared for weather related instances or buying when things are cheaper/buying in bulk. I think instead of making me look weird, it just makes me look responsible or frugal. It also gives me a good gauge as to if they are considering the idea and want to know more or if they are just blissfully unaware.
Instead of saying that I'm preparing for TEOTWAWKI, I normally talk about being prepared for weather related instances or buying when things are cheaper/buying in bulk. I think instead of making me look weird, it just makes me look responsible or frugal. It also gives me a good gauge as to if they are considering the idea and want to know more or if they are just blissfully unaware.
I envision this as cookie monster.
Wait for the discussion to come around on its own. Odd as it sounds, it can/will happen. Remember the ice storms and blizzards we've had recently where people couldn't get out and go anywhere and/or were without power for a week or more? Talk to them about how to handle those situations. Don't say "Well, if that happens, I have <blah blah blah> stored up." Say something like "It sure would be/would have been nice to have a couple of weeks worth of food on hand when that storm hit." Or maybe even "Boy I was lucky I got to the store before the storm came in and got my groceries."
I think it's OK to tell someone you have a propane/natural gas stove that works when the power is out, or that you cooked on your propane or charcoal grill when the power was out. "Sure it was cold out, but our food wasn't." That's giving them an idea to use something they may already have, and it's not weird to actually have a gas stove or a grill, so you're not a "crazy prepper" for having one.
Or, if you don't want to make suggestions like that, you can always just say "Well, how did/would you handle it if you knew there was going to be another ice storm and we were going to be without power for 2 weeks again this year?"
If you've got a friend that just started working after a long period of unemployment, or has a seasonal job, you can point out that if they had a few weeks/months worth of food on hand at all times, their unemployment checks and savings accounts would stretch farther. Even if the person you're talking to isn't/hasn't been in that situation, they probably know someone who has that you can hold up as an example.
Basically, get them started on the idea of preparing for things that "can actually happen". If they're prepared for 2 weeks without power or the ability to go to the grocery store, they're 2 weeks farther away from knocking on your front door. Once their foot is in the door on prepping as a "normal person", it's easier to start them down the road to "crazy prepper".
