Too simple a question to ask, isn't it? The one-line answer is that the number of trades that one should take depends on his trading style.
If you are a swing trader, you can use this calculator to see how much you can earn in a year, depending on how well you can trade.
Lets say that you keep an average capital of Rs. 3 lakh per trade, and achieve 15% average profit per winning trade, with a stop loss of 8% on losing trades. Now all your trades will never be successful, so I have kept only 65% as the win ratio.
If you can take 2 trades in a week, it turns out to be around 100 trades in a year. That sounds to be a lot of trades, but I am talking of 2 trades in a week, not in a day. With above-mentioned variables, and 100 trades in a year, it will earn you around Rs. 20 lakhs (Rs. 20,85,000 precisely).
What if you take just 1 trade a week i.e. around 50 trades a year? In that case, your annual profit will reduce to ~Rs. 10 lakhs (see Figure 1 below).
But if you can improve your average profit per winning trade to 25% from 15%, you get to Rs. 20 lakhs again (see Figure 2 below).
If you have a strategy that improves your win ratio, increases your average profit per trade, and reduces your stop loss level, the result will be far far better.
Use the calculator on top to see how each variable can impact your trading income, and decide what is optimal for you.
I use Pro-Setups script for my swing-trading. If you also want to try it, check it out here.
Note: This article is written for individual discretionary traders, trading in cash with no leverage.