There are several ideas that apply to most searches that are indespensable, plus several that are more search engine specific. AND , as in dogs AND cats . OR , as in dogs OR cats . NOT , this is either used as dogs NOT cats or dogs AND NOT cats . This will match dogs and cats and not match cats and dogs .
Every search engine has it's own features.
Has two types. It is easy to lose focus. Our suggestion is - bookmark the interesting sites as you find them.