Capsules: Separate the seed by hand-crushing the capsules, and then sift through a strainer or shake in a bag so the seed falls to the bottom.
 

Maple seeds: Separate pairs of maple seeds, if still attached. They can be planted with the "helicopter blade" still attached. They don't store well, so sow immediately.
 

Fleshy fruit: Place fruits in a jar of warm water and crush the pulp with your fingers. Let the jar sit in a warm place until it stinks: this will make separating the pulp from the seeds much easier. The pulp can then be removed from many fruits by hands.
For fruit with many seeds (e.g., berries), place some of the fermented fruit in a blender or food processor, add water, and then run the machine just long enough to mash the fruit (to avoid ruining the seeds, use a plastic blade and a slow speed). Allow the seeds to settle, then pour off most of the water and any floating pulp or seed ("floaters" are not good seed). If you are going to plant the seeds right away, they do not need to be completely clean, and can be strained out at this point.
However, if you wish to dry and store the seeds, they will need to be fairly clean. After pouring off the water with the floating pulp and bad seed, add more water, blend, and pour off excess water again. Repeat process until the water runs fairly clear. Strain the good seeds out with an appropriately-sized screen or sieve (very small seeds can be strained through pantyhose), and dry them.
 

Cones: Cones must be dried to remove the seeds. To preserve the seeds and prevent molding, spread out the cones on a screen or sheet in a warm place with good air circulation immediately after collecting them. Turn them every few days to prevent molding. When the cones have opened fully (a few days to a couple weeks), the seeds can be extracted. Cones can also be dried in an oven set below 100° F, but they should first be allowed to dry at room temperature for 3-7 days. If your oven will not keep such a low temperature, turn it off and use a light bulb on an extension cord to heat the oven.
Once the cones have opened, dump them in a large paper bag, roll the top shut, and shake the bag vigorously for at least 5-10 minutes (until you think your arm is going to fall off!). When you remove the cones, the seeds will be lying at the bottom of the bag. If you are not sure you have recovered all the seeds, put the cones back on the drying screen, wait a few more days, and try again.
An alternative to shaking is to place the cones in a heavy cloth bag (not your best bag, since you will get pitch on its interior). Tightly tie the neck of the bag shut with strong rope or cord, place the bag in a heavy- duty clothes dryer, and turn it on without heat the seeds will drop from the cones to the bottom of the bag.