First choose the two plants you plan on crossing and choose who is going to be the "mother" and the "father" (pollen parent). The "mother" flower or the one that will produce the pod (receive the pollen) is chosen right before it opens.

I take a small pair of sharp scissors and carefully cut around the base of the corolla tube. Be careful not to cut in to far as it can damage the ovary or stigma. When you do this it takes off the flowers stamens so it can not self pollinate and gives you easier access to the stigma.

Now to get the stamens from the "father". I simply choose a flower that has been open a few days but the stamens are still closed together. I simply pick the corolla off the plant.

I then take my scissors and make a nice cut on the upper part of the corolla tube.

Then I gently pull the corolla and it's lobes carefully from the tube and expose the stamens.

Now I carefully pull the anthers apart exposing the pollen. I then rub the anther onto the stigma. I usually use both sides of the stamens anthers to be sure pollen is covering the stigma well.

I then lightly wrap the pollinated flower end in clear plastic wrap but leave the bottom slightly open to prevent rot. This ensures in my dry environment (average humidity 15%) that the Stigma wont dry up to quickly. You will want to open the bag and repeat pollination a second time after a few days have passed to ensure pollination. Be sure to replace the bag. (This step can be skipped if you live in a humid place)

The bag can be taken off after a few days. The seed-pod will have began to elongate and twist. After about 2 months it will start to turn brown and dry out.

Here is a dried pod that I cut and allowed to finish drying out.

When the seed pod is completely dry I hold on to both ends of the pod and untwist it. This opens up the pod and allows the seeds to fall out freely. Now be sure to store them in a cool dry place until you sow them. :)