There's no denying it, there's nothing quite like the thrill of watching a
float shudder and keel over as a pike picks your bait up. As it slides away,
you pick the rod up wondering whether it's going to be two pounds or twenty.
Laying on is a simple method to master. It's virtually foolproof and if you
set it up right, it provides you with instant indication of a run. All you
need to do is fish a sliding float, set slightly over-depth and fix a weight
either on the trace or just above it to anchor the bait on the bottom and
cock the float. 
Let's start with stillwaters. The best types of float to use are the slim
balsa pencils, attached to the line waggler style via a ring at the bottom.
Most decent tackle shops stock them, or you can make your own at a fraction
of the cost.
The float is stopped with a stop-knot or rubber rig stop around a foot or
two over-depth. The weight varies from a couple of swan shot for calmer days
or shallower water, to four or five swan or a small or medium egg sinker to
cope with a wind or deeper swim.
It's worth plumbing the depth and getting to know the bottom contours of
your swim. Gravel bars, marginal shelves and the sides of drop-offs are all
potential pike holding features.
When you cast the bait in the float should lie flat on the surface on a
slack line. Place the rod in the rests, carefully tighten the line and it
will sit up. As soon as a fish picks the bait up, it'll either move the
weight and make the float keel over in the time-honoured lift bite, or slide
under as the pike moves off to swallow the bait. Wind down to the fish and
strike quickly either way to avoid a deep-hooked pike.
Hardly rocket science, is it...? And once you get the hang of it, there are a
host of little dodges you can use to sharpen up on presentation. I prefer
swan shots because it's easy to add or subtract weights without breaking the
rig down. I pinch them on the trace wire, rather than the line, usually 18
inches or so away from the bait.
If you make your own traces, slide an inch or so of fine silicone tube onto
the wire to pinch the shots onto. That way you can move the weights if you
need to without damaging the wire. 
On calmer days, you can get away with two or three swan shot, which will
just be enough to anchor the float so it sits up on a tight line. If it's
windy, you may need to add more weight to anchor it down, so you can sink
the line without the line dragging the float back towards you.
I prefer floating braids to mono for piking. Notwithstanding their low
diameter and lack of stretch, I like to know my line's on the top, out of
the way of any potential snags.
Obviously if it floats, the wind is going to blow a bow into the line. If
this tows the rig out of position, try adding more weight. If it pulls the
float under, slip a bigger float on. Making your own means you can knock
together a range of balsa pencils in different lengths and diameters for
around 25p a float in a couple of evenings.
Attaching floats to the line via a snap link swivel means you can change
them instantly should conditions require. 
Twitching the bait a foot or two every few minutes will often provoke a
take. You can also pop the bait up by adding buoyancy in the form of a balsa
stick stuffed down its throat or a bait popper (or a sliver bit of cork...)
wired to the bottom treble on the trace. Varying the distance between the
weight and the bait varies the distance the bait sits off the bottom - it
pays to experiment.
Laying on works a treat on slow moving rivers and drains too. In flowing
water, it's best to sit slightly downstream of your chosen swim and cast
upstream to it. As you tighten up, the flow should help drive the float
against the stop knot, making it sit upright.
You may find you have to fish slightly more over depth to stop the float
being dragged under, or use a bigger float to ensure it stays on the top
where you can see it. In stronger flows, which drive a pencil float under,
switch to a more buoyant through-the-middle slider, like one of the Drennan
Piker or Zeppler designs, or even the good old fashioned polyball.
Laying on is a great method if you're new to piking. As long as the float's
set properly and the line's tight, it will register a take as soon as a pike
picks your bait up.
One thing to avoid are the loaded float designs, which sit up regardless of
whether the line's properly tightened or not. In the wrong hands these are
potential killers, because a fish can pick the bait up off the bottom
without the take registering until it moves off, meaning a pike could
swallow the bait down before you realise it's on the end.
