Reflections - Watch out for reflections, the 're a guitar photographers worst enemy. Most guitars have a lacquer or poly finish which can be highly reflective. The easy way around reflections is to shoot your guitar at a slight angle so the reflection (which is often the photographer) is not vi sable in the photo. With LCD viewfinders it is often hard to see the actual reflection until you review your photos on a PC. I would suggest taking several test photos at different angles to determine your best shot.
Take lots of Photos - If you have a digital camera take lots of photos ! The're free and you will quickly realize that the majority of your shots were not quite what you were looking for. After playing with angles and lighting I find I toss out 75% of my photos so if I need 4 good shots I usually have to take at least 16 photos.
Try multiple angles - The angle of your camera can significantly alter the perspective of your photo. You will find that a slightly offset angle may give you a better result than you expected. Once again experiment, take lots of photos to see what you like.
Marking Photos - While experimenting with angles, lighting and reflections it's easy to forget how you set up your photo. I write my set up details on post-it notes then stick them on a corner of my work area. This allows me to see my notes associated with each photo. I can crop the photo in photo editing software to remove my notes.
Background - If you intend to use photo editing software to change your photo's background you might want to consider using a solid backdrop for your photo. This will allow the photo editing software to easily identify what the guitar boarders and prevent manual editing of photos.