Whenever entering the stock markets:
1. Be clear about what you want to do: Invest or Trade
2. If Invest - you have to play the waiting game after you pick the right business - ideal time period 3 to 5 years
3. If Trade - decide if it is going to Day trading or Positional. https://twitter.com/Kishoreciyer1/status/1322808367350386689

4. Always understand your risk handling capability - if you cannot handle a losses you shouldn't invest or trade - NIFTY scrips itself see ~30% swings in a year on an average, others might see more
5. Always fix the quantum that you can afford to lose, could be 10%, 20% or 50%..

..but don't ever not have a figure in mind before entering the market - if you do not set a limit you'll definitely lose your capital or you'll average down on losing positions
6. Definitely have a set strategy for investing or trading, follow it for at least a year before..

..revamping it completely.
7. It is always good to have an Exit in mind whether you are investing or trading - if you do not have it, you'll lose sight of your investments
8. Learn to average up and not average down!
9. Always have a Plan B and Plan C if Plan A doesn't work

10. Never never ever trade to generate monthly income to pay your commitments! (there are very few ppl who have done it successfully) Trading and Investing should be used only to build wealth!

--- will add more the list as we go ---