More distant trips will usually require car-pooling of some sort. Set a time and location to meet and stick to it. You should provide everyone a copy of your itinerary ahead of time so if they are late, they know where to find you and how to contact you (your cell phone).
Shuttles also require a bit of planning to avoid wasted trips. Normally, you want the largest vehicles at the take-out like vans and pick-ups. Dry clothes and a cell phone need to be in a take-out vehicle as well. Prior to leaving the take-out for the put-in, check and see if all drivers have their keys. I also like to pack some beverages and snacks in the take-out vehicles as people are typically hungry and thirsty after river trips.
If you are using a shuttle bunny, make certain they know when to expect you and be there on time. I also like to research neat things to do in the area off the river so the shuttle bunny has a good time as well. Sometimes the shuttle driver can follow your party while you are on the river and take pictures at key rapids.
Some runs can be quite remote or have severe towns people problems. These runs will usually require hiring someone to provide a shuttle. A really good local example is Muddy Creek in Pennsylvania where they tow all vehicles located anywhere close to the put-in whether they are legally parked or not. Once again, make certain you arrive at the take-out on time or a bit ahead of your planned arrival.
In areas that have had a number of recent break-ins, pack your wallet, drives license, and credit cards in your dry bag and secure well inside your kayak. These troublesome locations are typically well documented on the local canoe club websites. Some good examples are Anglers Inn, Violet's Lock, and the Lower Gunpowder River. If thieves don't see anything of value and continue to strike out, they will look for better opportunities elsewhere.