After location bait and it's correct presentation is the most important factor governing success or failure. No matter how expensive your tackle is, if the fish won't bite you go home empty. Freshwater fish can go several months without eating, most marine fish can not, indeed many marine fish will die if not fed several times a day( a big problem for aquarists rather than anglers). Fish will eat a wide range of prey as cutting open the stomach will show but these are not always the best baits to use. Remember your bait is not the only piece of food in the water, the secret of angling is to make the fish ignore everything else and take your bait instead.
Fish are not stupid, they want as much food as possible for as little effort as possible. This is known as optimal foraging theory, and although a contraversial subject amongst ethologists it's well worth remembering. Imagine a bass spotting a sandeel some distance away, first he calculates the energy he'll use to catch it then balances it against the energy gained by eating it, only if the pay off is greater than the effort will he bother. No fish is going to swim very far off course to pick up a puny little worm on your hook, imagine driving to the out of town supermarket just for one can of beans. This is the first rule DO NOT SKIMP WITH BAIT. Be generous, make it worth the fishes while to stop chasing that shoal and pick up your static large portion.
A fish can be said to show a preference for a food if it seeks out that item despite other food items being more available. This is the second rule STICK WITH THE WELL KNOWN BAITS (Yes we've all heard stories of some guy sticking a cream bun on a hook for a laugh and landing 30 lb cod). If one bait does not work try another as different species prefer different food and the colour of the water can play a big part. If you have an idea for a new bait try it out when the fishings good, if everybody else is catching bag fulls and your frozen fishfingers are too then your on to something.
Rule number three is MATCH THE SIZE OF YOUR BAIT TO THE SIZE OF THE FISH YOU EXPECT TO CATCH. Cod have large mouths and appetites to match, flatties have little mouths and cannot fit a size 6/0 hook laden with a mussel and lug cocktail in their gobs. Match the size of the hook with the size of the bait, a small hook buried deep inside a bait is well protected and the fish will not be impaled. If you are fishing for the smaller species it is better to use a 2-4 hook paternoster and spread the bait out rather than lump it on one hook. A pennel rig (see rigs) is two hooks in the same bait and increases the chance of contact when large baits are used.
The final rule is PRESENT IT PROPERLY see rigs. A lugworm suspended 3 ft above the seabed will set alarm bells ringing that somethings not quite right.
THIS IS NOT AN ADVERT. IT'S TIME WE KNEW.