Read the financials of the stocks, the news around it, and analyst sentiments around it.
Then check the growth rate for every quarter and recent investments it has.
If everything seems green to you then according to your risk appetite, invest.
Check to see where the stock stands in the 52 week level chart.
This is the most simple approach to it that I could think of, obviously people out there do very deep analysis of all the ratios and market trends but it's very complicated for a normal person.