There are a few choices when it comes to bait, the big two are bread crust and dog biscuits. These are fairly instant baits so I would suggest trying them first. Next on the list would be floating trout pellets followed by pop-up boiles, marshmallows and corn pops cereal. Bread is nice because it is highly visible and will shed small flakes as it softens up in the water adding to its attraction. Dog biscuits will disperse their oily scent in the water pulling the carp from the depths. The kinds of dog biscuits to use are the small ones that they mix with meat.
There are many terminal rigs for surface work. As a rule of thumb the less you have on the line the batter off you are, but there are times when some weight is needed to help you get your bait to the fish. Surface rigs with floating weight are generally similar to sinker set ups with the exception that the sinker now floats. The float/casting weight is called a Controller and there are many variations that are meant to fool the fish by blending in with the surroundings. Others can even hold the leader off of the surface with just the hook touching so the fish can't see the leader! One of my favorite surface controllers is widely available in the States already, the humble bubble float. These are clear plastic floats that can be filled with water to give them weight for casting. The best bubble floats are pear shaped making them easier to strike the fish.
A fairly long leader is normal to keep the bait as far away as possible from the controller as you don't want the fish to see the float. The leader may also be greased with fly leader floatant to help keep the bait up on top.
Hooks need to be light but strong and sharp (check out he Kamasan B982 X Strongs), sizes depends on the bait. For bread crust I like to use a size 2 or 4 which is pushed through the dark crust into the white middle, the whiter part is then squeezed onto the hook to help keep the bread on while casting and when in the water. Pellets and biscuits should be fished tied tight to the back of the shank of the hook, dental floss works well. Alternatively the dog biscuits can be soaked in water or flavoring for a couple of hours to soften them just enough to get them on the hook. If you can get away with it then no weight except for the bait approach will pay off, as it is less likely to spook fish.
Another very good way to present surface bait is right at the edge of the water next to the shore. In this case all you do is poke your rod through a gap in the bushes, place the rod on rests letting the line hang straight down with the bait held just on the surface. This is the ultimate presentation as there is no line in the water for the fish to be wary of! When doing it this way it is best for you to keep low, sit back a little way from the shoreline and rod. The best time to try the under the tip method will be early morning and at night, just make sure that you have a good baitrunner or the line clipped up!
Slip sinkers can be used with surface baits. All you do is tie your leader to a swivel, then comes a shock bead then a slip sinker. Once the rig is cast in the line is payed out until the buoyant bait pops up on the surface.
In an actual fishing situation the first thing to do is put out some free baits with the aid of a slingshot. Then the free offerings should be observed, bluegills will usually show up straight away picking away at the bait. The you may notice a large swirl, sometimes you may even hear the slurp as the bait disappears. Once you have seen a few of the freebies disappear then you need to cast out to these feeding fish, accuracy is imperative. It is best to over-cast, then draw your bait slowly back to where the fish are feeding. For my surface fishing I like to use my North Western Kevlite float rod with a fairly light line, its action is perfect for getting the bait smackon.
Once the hook bait is in position get ready for heart stopping action! Quite often the fish will home in on the bait only to nudge it, then disappear without taking. Your heart sinks, then all of a sudden you see the broad back of this big fish coming right back toward the bait again. Your pulse is now racing, then you see a huge swirl and the bait disappears. You strike, the surface explodes with the fish causing a bow wave as it leaves the scene of the crime, line flying off the spool!
Grass carp are often taken on surface baits, ducks can be a pain, same goes for turtles! The first carp that I ever caught was from the surface, I will never forget that fish.