Obviously, you're first probably going to do some research to find parts that meet criteria you need (for example, an LDO regulator with low drop out voltage to minimize loss), or a capacitor with a higher voltage rating than another one.
But what about manufacturer/part/etc? Say you've got a part my ON semi, Micrel, Maxim and TI. Datasheets are similar, features are the same... What makes you choose one over the other (forget about any cost differential for a minute).
Second question: Do you/have you ever chosen "multicomp" over another brand? Newark.com stocks parts by "multicomp" which as I understand it is just a variety of companies lumped into one, but given say, a ceramic capacitor. All things being equal, would you pick mutlicomp over Kemet/another brand?
I'm still learning about circuits and such, but when I go to pick parts for my projects, I can't always see a benefit to one vs the other ( an 8pin header by multicomp is the same as an 8pin header from say, Tyco..."i mean it's plastic and metal right?, so why is tyco 60 cents more" kinda thing).