One of the ongoing difficulties in the crochet world is the nature of the foundation chain. Knitters don't have this problem. Casting on usually creates a nice elastic (if sometimes floppy) starting edge. Knitters instead have difficulty with tight bind off edges. Since every crochet stitch is self contained, final rows pose no problems for crocheters.
Because of this problem, crocheting garments can be problematic. Keeping the foundation chain loose is really important for a good fit. Some crocheters, especially newer ones, also have trouble creating blankets and other four sided items, because the foundation chain cinches in that side of the piece, making it uneven. Here are some tips for working around this common problem:
1. The patterns always say to chain loosely. You can help this along by doing the chain with a larger hook. I use a hook two sizes larger (starting with an I and switching to a G, for example) and then switch to the hook the pattern calls for in the first row.
2. Try to find patterns that are worked in the round from the center or on the diagonal.
3. With garments, try patterns worked from the top down, have a shirttail edge (in other words, the side seams are open on the bottom inch (about) of the sweater, or orient the pieces so the chain edge is on the top, and partially consumed by the shoulder seams.
4. Never start a project when you are angry or stressed.
For more help with this problem, maybe Practical Crocheter will do a post about foundation stitches.