Anything you buy in the market you got to have odds on your money. Lets suppose you buy a stock and you risk 1000 rs on any stock(1000 rs = Entry price - stop loss) if the entry price of stock is 100 rs and SL is 90 rs you should buy 100 stock that is if stock were to hit SL max you would lose is 1000rs .i.e 100×10.
That's how you should be creating a portfolio every stock should get equal risk. Depending upon the market condition generally i target minimum 1:3 Risk reward( RR). I dont sell when i reach 1:3 RR thats minimum i target. At times you can easily get 1:5, 1:10, 1:25.
Currently the market is in a very mature trend. 80 90% of the move is over. Anything you would buy right now SL are going to be deep like more than 7,10,12%. So what are the odds that things are going to move double of the SL %. Best R:R currently you can get from the market is 1:1. So wait for the market to fall or consolidate. Even if the consolidation is sideways or we get a good fall of 5,7% on the index level, then bring the fresh money when the new cycle starts.
R:R IS THE MOST CRUCIAL WHEN YOU BUY ANYTHING. The day you will get the hang of it you will save yourself from blunder. If you still wanna buy do it through the SIP route. Buy small small quantities on daily/weekly basis this way you can benefit from volatility.