What are some tips to help prepare your body for major surgery when you are a hard stick for IV placement besides increasing your water intake?

Warm towels. Sometimes a warm, wet towel wrapped around the arm can help to dilate the veins. Keep it wrapped for about 10 minutes. Ask for an anesthesiologist or nurse practitioner to place the iv.
Exercise. Exercise helps increase blood flow to certain parts of the body. Try lifting weights with your upper extremities daily for at least a month before surgery. Please consult your physician before starting any exercise program.
Slim down, lose # Subcutaneous fat (more common in women than men) makes finding forearm veins more difficult. If you are little bit overweight it makes it more difficult still.