Rule #3: Find your focal point.
Before snapping your photo you should first consider the composition. Where is the focal point -- the area where the eye naturally falls? Is it the lime wheel garnish? The ice ball in a rocks glass?
Once that's determined your next task is to compose your photo in a way that highlights your focal point.
On the grid.
Ever noticed on your camera there's an option to add a grid to your view finder or screen? Two horizontal lines intersected by two vertical lines. This grid is available so that you can apply one of the most well known rules of composition -- the Rule of Thirds. While it isn't necessarily a strict rule, I find that it helps to create for engaging photos.
Originally used by painters, the rule of thirds helps to divide your shot into, well, thirds. Simply place your subject along the vertical and/or horizontal lines. Your focal point should fall at any of the intersecting points.
Here's some examples of how I use the Rule of Thirds to compose my cocktail photos:
Example #1. In this first example we have a cocktail with a celery garnish. Notice how the celery lines up with the right vertical line. The cocktail itself is placed in the right two-thirds of the frame. The bar patrons are all lined up along the top horizontal line.
In example #2 the cocktail is placed along the first vertical line. Taking a nod from landscape photography, I've created a horizon by placing the bartop along the bottom horizontal line. By dividing the photo this way your eye naturally falls on the focal point -- the top of the cocktail.
Example #3. What if your photo has two focal points? In example #3 I've placed the two martinis at two intersecting points. The martini in the foreground is placed along the right vertical line, the martini in the background along the left vertical line. Your eye is guided from the front to the back taking in both glasses.
The Rule of Thirds is a great way to train your eye to compose great photos. With practice you'll gain the confidence you need to become a better photographer.