Tom certainly outlined some very important key elements, so I'm going to take a very simple approach to pre-fishing. First a little make-believe here. You are a 20 year guide on your home lake. You have folks booked about 3-4 days a week for several weeks straight. So do you take off for some much needed rest those other 3-4 days? Nope. You follow the fish every day. In effect you are pre-fishing for an event that means money to you. The key word above is "FOLLOW".
Now back to reality. You have a regular job and fish tournaments when you can. No way can you "follow" bass, even the day before a tournament, right? Wrong. You observe what Tom wrote, some of which is season-long procedure, but do whatever it takes to tune yourself up for the big day. So what's more important today? Getting some bites? Or finding bass? I say find the bass the same way a guide often does it. He doesn't wish to sore-mouth bass meant for his clients, either. The guide has a big advantage over you, the weekend warrior, maybe never having fished his lake before. Find the bass and take note of every detail possible about where the bass was. Other bass will be in similar places around the lake under the same conditions. Finding bass on a strange lake is a step towards following bass daily. The difference is you followed that one day. Whoever follows the most often does the best, why local guides in a tournament are often highly favored to win. The fellow not only followed bass daily, but slipped off to alternative places to confirm bass were NOT over there. That frees his mind to focus on the places that DID have bass to follow. It can be tormenting to keep thinking you ought to be over there instead of here. You get there and regret leaving here. Guides don't bother themselves with that on their lake, and pros stay pros by conquering that uncertainty problem. They know where to go and not to go. You do the same as much as you can.
Pre-fishing one day, especially only the day before is to me risky since conditions can change and leave you with no clue where the fish go under different situations. If the tournament is over a weekend I think it's highly advisable to fish at least one weekend before the event. I'd plan to do that way before considering pre-fishing the day before (probably a Friday). Where do the bass go under high pressure? Do they stick around ramps where nobody fishes, or go to the least obvious places nobody ever fishes? What happens when the wind is out of the N, S, E or W? How is it with every cove and other good looking spot taken up by locals all day Saturday?
Use pre-fishing crankbaits/spoons/ etc. with hooks bent in. Keep some trebles on hand already bent for pre-fishing. Not many lures will swim right if you clip hooks too much reducing the weight and balance. A bass will bite it and if you can handle tournament level fishing you will know a bass bite. Often they will hold onto the bait right up to the boat. Just the feel of the fish ought to be very familiar. I usually know the difference before seeing the bass. Wipers sometimes fool me. A catfish might go for a crankbait, but by now you ought to know the feel of a cat. But how many times have you caught those when bass fishing? You know the Frenchy surrender of a pickerel. Get that telltale bite feel and let it go. Immediately assess the spot with sonar. Were there more with that one? Exactly where was that fish when it hit? Did bass follow the lure in? Mark that spot, and look for other places like it. That to me is finding a productive pattern. It might not work other times of day, or on the big day. But it's the best information you can get.
One last comment comes to mind for now. You might not call yourself a worm angler. But I recommend becoming a novice worm angler at least just to pre-fish to locate bass. It doesn't require becoming a Larry Nixon level worm angler. You can always return to catch them using your confidence lures on the big weekend. I don't know of a better all around search bait that can be fished without a hook more effectively. Most any bass will swallow a hookless plastic worm whole and keep it until it breaks surface. They love to eat worms with big hooks too. I've had to bring pre-fishing bass into the boat to extract a hookless worm sunk deep in the stomach. Rig them with slip sinker as usual, but tie on a hook shank with entire hook bend removed. Slide the shank inside the worm, bury the line eye, then taking a piece of 80# mono spear it through the worm, through the line eye, and out the other side of the worm. Melt the tag ends of the mono to make buttons that will hold the worm on. Cast it, flip it, pitch it, but don't set it. Let a bass take it, swallow it, then ease into a fight. Remember, all you want is to get that bass feel. If you can get it close enough to see it, all the better. Once you do that, you have confirmed all your scouting to have led you to a bass. It'll likely still be there when you need it, wanting that worm back.
Jim