Do you remember the last time you have been in a public park with a lake? You probably saw a lot of people casting away some bread (or food) to the ducks, and you saw many carp coming when the people started to feed them. That's kind of prebaiting ! Because the people feed like this these fish and carp are used to this kind of food in this specific area.

Do that by yourself by prebaiting some spots, somewhere where you saw some carp. Prebait about 2 lbs. of boilies a day during 3 or 4 days in a row. You can use corn but prebaiting with corn tends to attract catfish, crayfish, turtles or others than carp. Also the improper use of corn can result in the death of many carp. I know that it is boring to go somewhere just for prebaiting and do not fish but try and you will be extremely surprised by your results. You will catch many carp this way, just for you and your friends. You can prebait 2 or 3 good spots all year round. It will be better and better each time and also you can switch from one spot to another. Maybe you'll find out that one of these spots is better than the others.

It will be better, because the fish will remember it as a good place for food (EASY FOOD). That's simple. My friends and I catch almost 15 carp (150-300lb) per angler and per fishing-day, sometimes much more. Sometimes also we blanked but only 3 or 5 times a year. Consider that! We fish around 40 weekends a year together. It is not a lot of blank, but that's true we bait a lot. If you don't do it this way you will probably just catch just a few carp.

Fishing in a river
Lay out bait regularly and in generous quantities, because boilies or corn get swept away by the current. The more bait you lay out, the better your results will be : at least 2 lbs. of boilies per day.
It’s impossible to saturate an area with food, for the current eventually sweeps everything away. River carp swim around far more than lake carp.
The faster the current, the nearer the carp will be to the bank (95% are taken from between 3 and 25 yards from the bank).