One of the keys to effective prepping, as I see it, is knowing what exactly you’re prepping for. Perhaps “exactly” isn’t the right term; for what envisioned contingency are you doing your prepping? As should be obvious, the preps for a natural disaster (flood, earthquake, hurricane) would be different from the preps for a man-made disaster (terrorist nuke, etc.).
One way to break down the list of possibilities is by looking at the time frame of the collapse. Will it go down quickly? Slowly? In-between? Again, the preps will likely change: a slow-motion collapse is a different scenario than an overnight one.
To my mind, “sudden” collapse scenarios include the above-mentioned terrorist dirty nuke, or most of the environmental scenarios (earthquake, tornado). In these instances, things will change overnight, at least in local terms. The savvy prepper will be able to bug out to a safer location and ride out the aftermath.
“Moderate-speed” scenarios would cover scenarios such as global pandemics or financial collapse. In these instances, the collapse will probably happen over a period of weeks-to-months. If we’re watching, we’ll be able to see them coming near the beginning, and direct our preparations towards the particular event that’s coming: breaking out the gas masks and antibiotics, or shifting assets into tangibles from intangibles.
The “slow” collapse scenarios are probably the most insidious, happening over years-to-decades. These would include peak oil and global climate change (whether man-made or not). They’re moving at such a slow pace they’re all but invisible to us; our minds are generally not built to “see” that long a time-frame.
In terms of likelihood, they are all different, as well. Myself, I don’t worry much about the “terrorist-nuke” scenario; it’s possible, but difficult and unlikely. I’d say the three most likely are peak oil, financial collapse, and pandemic. (This is, of course, discounting “natural disasters,” such as earthquake, hurricane, or tornado, all of which happen regularly.) I rate them this way following simple reasoning. Peak oil is upon us, either just past or in the very near future. Financial collapse looks more and more likely every day–and, to an extent, it goes hand-in-hand with peak oil, in the Long Collapse scenario. A pandemic is only a matter of time, and we aren’t exactly helping things with our profligate (and inappropriate!) use of antibiotics; MRSA is already out there, XDR TB is on the rise, and I’m sure there are others.
All that being said, my family’s plan is to take them one at a time. We’re doing what we can right now to alleviate the damage from whatever quick collapses (personal, local, national, or global) we can envision and think likely. We are enacting longer-range plans to cover moderate-speed collapses, and (slowly but surely) are positioning ourselves to handle the slow collapses. What are you doing to prepare, and what are you preparing for?