Give us some stats, like experience, etc.
Also, try doing a search on carb-loading, fat-loading, glycerine, taraxatone, sodium retention, pottassium, etc. These are all factors that influence appearance. You want to eliminate subcutaneous water. I am not an expert at this. Some people try to carb load before a contest or photo shoot and end up retaining a lot of water.
If I wanted to improve my look for a photo, I don't think I would carb-load too close to the big day. I would be too scared of "spilling over". I might carb load and leave 36-48 hours to "dry-out" if I was retaining too much water. Going into the sun or in a sauna can help if this happens. Taking diuretics for a few days before a photo can help (taraxatone and ephedrine-caffeine may work). Glycerine pulls water from under the skin and into the blood stream. If you work your muscles after this (pump yourself up), it helps to volumize your muscles, too. Takes maybe 5 hours. Some people like to take a swig of wine to make their veins more visible for that vascular look.
There is so much involved here and I don't really know much about it. Try asking some experienced competition bodybuilders about pre-contest dieting in preparation for a show.