You've got the pattern and the needles, the hoop and the threads.  But what about fabric?  Fabric is probably the most important choice you will make.

First, there is color.  Some colors are harder to work with (such as black), so should be steered away from them if you have troubles with your eyes.  At the same time, black can make a striking background for many items and subjects, such as floral, fruits, and even holiday themes.

Second, you should consider type.  Some fabrics tend to fray more than others while you are working on them.  If the project is going to be a long one, consider using Aida, or a similar weave, as they hold together a bit better than linen type fabrics over prolonged rubbing and moving, etc.  Also, the fancier types of fabrics require more focus on the project while your working.  If you have to go up 2 and over 2 for every stitch, you really better be paying attention and not trying to catch up on your favorite show. :)

Third, which actually somewhat is connected to the second, consider the count of the fabric.  The count changes the size of the finished product, decides the amount of threads you will use, and can set the mood for the piece.  A fancy Victorian floral wouldn't really be appropriate on an 11 count piece of fabric.  It would look too awkward and the daintiness of the pattern would be lost.  On the other hand, if you are stitching a more primitive piece, your project would probably look good on 11 count fabric.  14 is the most widely used, as that works well for most patterns, gives you a larger finished piece, and is fairly easy to see and stitch.  16 ct is just a bit more refined and you can get better coverage with your threads.

Most of all, just enjoy your project. :)