Good advice all, above.
Bring someone along who knows how to track if you have never done it. Depending on terrain, this can mean the difference between bringing home the venison or going home empty handed. Especially when bow hunting, especially first time out.
If you can't do that, read up as much as you can about it.
After the shot, watch as long and closely as you can to see which way the deer went. Listen, too. Wait at least 30 mins or so before going after a wounded deer. ALWAYS mark the last spot of the blood trail that you find when it seems to peter out. Limit the amount of trampling about on the blood trail so you don't overlook anything. Look at taller grass/brush for blood. It's not always on the ground. Bring a GOOD flashlight. Deer shot in the a.m. are easier to track in the day, than deer shot in the evening and tracked after dark. Leaving a deer in the evening and coming back to look for it in the a.m. might have to happen, but if there are coyotes in the area, you might not find much and nothing you'd want to keep.
Most bow shot deer, if hit well and it's a clean pass through, will leave a really good blood trail. If not hit well, or hit high, or in the wrong place, there may be very little blood, or some at first and then nothing. Sometimes an arrow may stick in a bone and not pass through, so there may not be a good trail. Don't give up. Too many hunters I've known will give up too easily. It's a sick feeling to leave one out there, so don't be that guy.
Bad hits can happen due to wind, bad range estimation, branch deflection, deer jumping the string, clothing/jacket catching your string, etc. Just do everything you can to make the perfect shot the first time, but be prepared to track if needed.
Good luck!
Edited to add: I found early on that the quickest way to failure is not drawing at the right time. If there are three does in front of you and a buck, they ALL need to be preoccupied or looking the other direction before you make your draw. There is always one old wary doe in the bunch that will tip the others off if she sees you draw. A single buck or doe can be fairly easy to draw on if you wait for the right time. It gets exponentially harder when there are two, three, four, or more deer together. You have to watch all of them for the right time to draw, not just the one you're after.