The chain stitch is the bais of all craft work. There is no design, however intricate and beautiful, that does not largely depend upon this stitch and its various modifications for its entire structure, and once it can be made perfectly and easly, any crocheted article may be produced with a smoothness and finish only to be attained by evenly made stitches.
The methods of beginning a chain are numerous and are varied according to the manner of holding the thread or the proficiency of the worker; and generally, if the method is awkward, it is the out-come either of incorrect instruction or name at all.
Some who crochet tie a single knot and draw a loop through it for their first stitch; others produce the same result by making a twist of thread in the left hand and with the hook in the right drawing a loop through the twist, thus forming a “slip knot”, as it is commonly called.
The twist of yarn is formed and then held by the thumb and forefinger of the left hand, the yarn is then arranged over the fingers by the instructions given below before the hook is inserted in the loop.
When the latter is drawn tout, both hands will be in proper position to go on with the work out one. Or, the knot may be drawn, tout and the yarn or thread then arranged as follows: hold the work, as it progresses, between the thumb and forefinger of the left hand with the thread or yarn passing over the first finger, under the next two fingers, and over or lightly around the fourth or little finger, to produce a sort of tension by which to tighten or loosen the yarn according to the requirements of the work.
Hold the needle or hook in the right hand in much the same position as a pen is properly held in writing. A strict observance of the methods of those who crochet has proved that the majority of them hold their work in this way.
Hawing made the slip-knot and arranged the yarn over the hook as seen in figure n.2 and by a slight movement draw it through the knot, slipping the latter of the hook as in figure n. 3. This movement repeated forms the chain.
To widen in plain crochet work, two stitches are made in the same place; and in narrowing a stitch in the preceding row is skipped at the point to be narrowed.
Source: The Art of Crocheting