For short term survival post bag-loss I'd worry less about toiletries and more about clothes.
Most hotels will supply you with a (crappy but serviceable) toothbrush, razor and other basic toiletries on request and if not (ie. you're in a hostel) you can probably replace the basics for a few bucks if needed. Plus, the complication of having to take anything sharp (scissors, tweezers, nail clippers) and large liquid containers (shampoo, sunscreen, moisturise, etc) out of your toiletries bag every time you catch a plane is a major hassle.
Far better to just carry some versatile, destination-appropriate clothes and underwear.
Also, in terms of general preparedness:
- Carry your important document, like a copy of your insurance details (!), important contact numbers, a copy of your itinerary, etc. in both your carry on, check in luggage and online (Dropbox or email them to yourself).
- Before you pack, lay all your clothing, electronics and anything else your taking out at home and take some photos. This will help hugely with insurance if you need to show or remember what you packed and to estimate value.
- Also, take a photo of your luggage itself on your phone or something. The first thing the airport staff will ask you is "what does your bag look like" and Being able to give an accurate description or photo can help them locate and identify your stuff.
- If your loose anything report the lost to your insurer straight away. They might have important instructions, requirement or limits on what you can spend to replace your stuff/deal with its delay. For example, if your bags are delayed there may be a daily allowance you can spend of replacement clothes.
- Obviously, keep receipts for anything you need to buy as a result.
- You can't replace photos. If you're on a long trip, periodically drop in at an internet cafe, burn them to a DVD and mail it home. It'll only cost a few bucks and provides security the best insurance policy in the world can't.