I believe most of you have experience of shopping. Being a smart shopper, First of all, you need to do a pretty good research before taking next step. You need to know your budget, needs, what you have, gather information of potential targets and get some advices from friends or family.
And then you take the next step. You go out with a plan and targets on hand to make observation in person. You may be able to negotiate with sellers or find out better deal on sale by accident.
What do you do next? Buying? No, you go home and think about all the options you have on hand for few days. You don't buy immediately because you may buy things on an impulse then regret it later on. You don't consider too many days because someone else may take it before you decide to buy.
The same thing goes to signing free agents and making trades as well.