Never invest in any idea you can't illustrate with a crayon
Visiting stores and testing products is one of the critical elements of the analyst's job.
You can't see the future through a rearview mirror
You should not buy a stock because it's cheap but because you know a lot about it.
Searching for companies is like looking for grubs under rocks: if you turn over 10 rocks you'll likely find one grub; if you turn over 20 rocks you'll find two.
When even the analysts are bored, it's time to start buying.