Hand cards are a fairly inexpensive alternative to drum carders and professional processing for fleeces. They are rather slow to use at first, but as you practice, speed will come. The trick is, to card your fleece a little at a time, everyday. When you have built up a good amount, you can spin as you card. It is a longer process, but one that is full of satisfaction, and is relatively inexpensive. If you can purchase a raw fleece, you can wash and card it yourself and save quite a bit of money.
Before you begin to card, you need to use a dog brush (or a brush designed for it) and clean out the teeth of the cards well to avoid contaminating the new colors. Just take the brush and starting at the top of the cards, brush downwards towards the handle. All of the excess fiber should come away on the dog brush.
Once you have purchased and washed a fleece, you should go through it and open the fibers up well, picking any debris that you see while you tease the locks open. Now you can load the card with your newly teased locks. You can tease it all, then card, or you may also just tease enough to load the cards.
To load the cards, hold some wool in one hand, and gently draw it across the card. Some will catch on the teeth, keep adding more wool, until you have a handful or so loaded.
Alternatively, if you are not carding a very fine wool, like alpaca or angora, you can just lay the teased locks on top of the card. Try it both was and see how it does. A very fine fiber may break, but most sheep's wools will be fine using this method. For my Shetland fleeces, this seems to clean and card the wool better.
Now you will draw the second card across the loaded card. There is a feel to this action that comes with practice. I have been told by some that the teeth shouldn't come into contact with each other at all. My experience has been that this doesn't process the wool enough.
My "expert" carding friend, Gail showed me that the teeth should connect just a little bit. Enough to really card wool, but not so much that the teeth of the card get bent or mangled. It shouldn't be arm wrenching, but should be a little work to pull the wool through the cards. Like spinning, I think you just have to plow along, then suddenly, it works.
Once you have carded this batch, you may load more on, with either method, and card again. Once your cards have a big enough batt, you can peel it off, pulling from the top towards the handle. I will usually re-card, then roll into a rolag or my version of home made roving.
To make a rolag, all you have to do, is begin rolling the batt from the top towards the handle. As it rolls the fiber will come away from the cards, and you will have a little roll of wool perfect for woolen yarns.
For a more worsted type yarn, you can pull the batt off, and spiral roll it, end to end so that the fibers stay more parallel. Then you can lightly pre-draft it by pulling the fibers a little to align them better. I like this method the best, but some prefer rolags.
To spin the rolag, just begin pulling fiber from the end, and begin spinning. The roving will also spin up about the same as regular roving, except your pieces will only be about a foot and a half long.
Alternatively, you can spin a very fine and nice thread right off the cards. This makes a very nice alternative to rolags or rovings. but it takes a little practice to get the feel for feeding the fiber off the cards. It will also help if you keep as much of the fiber on the ends of the cards as possible.
Good luck, and I hope you enjoy learning to card your new fleece!