Where do you go to find out how much a company is worth.
How can you determine if its indeed undervalued & how will you know when is the best time to sell their stock.
If you get someone to figure it out for you, then typically, the company is not undervalued anymore.
You should do your own financial calculations and try to figure out the value of a company if you're inclined. The problem is that even if you identify an "undervalued" company, there's no guarantee that the company won't lose value in the mean time or that the company doesn't stay undervalued for reasons that aren't in the financial statements. Also, you need a catalyst for Wall Street to realize that it's undervalued so that they can price it properly.
There's no "best time" to sell either, but it's typically when it has hit your take profit level or when it's valued fairly so there's nothing to be gained by holding onto the company anymore.