1) Walk up and down the bank (or around the edge of the water) and scan for any visible fish or clear patches on the river bed. A set of polaroid sun glasses and a wide brimmed hat are very important for fish spotting in summer.
2) Examine the lake bed by using a spare rod and lead weight. Cast out to a number of positions and feel your way along the bottom.
Depending on what you find along with the specifics of the immediate surroundings, you should be able to establish what might be lurking beneath.
3) Once you have established your chosen spot, Use a marker float to pinpoint it. Then, using a second or even third rod, cast out to this position, as close to the marker float as possible. Then retrieve your marker float.
Before you go:
Dont take everything you own, you'll need to move about and fish different swims for the best chance of catching well so travel light for easy mobility.
Check the rules of the location you are going to so you know what you can and can't use. For example, Some fisheries ban both live and dead baits and some are very specific about barbs and barbless hooks. Check all of their rules to make sure you take the correct equipment and bait.
Check the weather conditions and temperature -
Winter can yield some of the best specimen sized fish. However a Very harsh winter with very low temperatures and not much will be biting except the cold at your fingers!
Not many fish feed in flood waters with the exception of Barbel who will then feed for Britain, especially just after a cold, rainy spell.
In hot weather the fish bask on the surface.
If the location you are going to has heavy boat traffic, take a back lead with you which slides down your line and keeps your line well below the level of the boats.