Lighting is an interesting take, and perhaps the most important element to your photograph. You want to avoid those harsh reflections and unwarranted spots on the glass, but still illuminate your liquid amicably. While tricky, you can still easily photograph beverages under correct lighting conditions, especially when manipulated.
Back Lighting - While backlighting is often frowned upon in the photography industry, it does help offset bouncing light into a controlled direction. Counteract dreaded bright spots by placing your light source behind the main subject to gently highlight the glass in a more flattering way. Even when using side light, point toward the back of your frame for more even shadows.
Hard Light - Again, harsh light can be a bit difficult to work with under normal circumstances, but bright tones can add a powerfully dynamic to your drink photography. We’re so often told to utilize a more soft, diffused light but sometimes that simply isn’t enough vibrance. I have often found drink photography to be the perfect opportunity to capture photos using pure, undiffused light to encapsulate the textures on the glasses, creating almost a prism effect. Remember: the further the light is away from your subject, the longer the shadows so really play with your scene and find a happy medium.
Natural Light - The free, least adulterated source of light is one that comes from your nearby window (or outside your front door! Any excuse to get outside is fine by me). However, if you are photographing in closed corridors, shooting indoors is a whole different ball game. Because indoor lighting creates a challenge for finding excellent light throughout the different rooms, you must strategically photograph during the brightest parts of the day. I find that midday is the perfect time for a vibrant, bright window-lit room.