Not doing enough research: Not doing personal market research before investing can prove to be a big blow to your investment.
Going by the words of your trusted sources, such as, friends, experts, brokers might pay at times but ultimately it's your money that you are risking in the stock market and thus your personal touch to the investment portfolio might make a big difference to the profits incurred at the end of the day.
A solution to this might be asking your broker or your friends to teach you the market strategies so that you gain enough confidence to pick the correct shares and invest on them.
Moreover, a thorough study of the market trends over a certain period of time might also prove useful and can be done by drawing data and information from the various online sources easily available to you nowadays.
Investing on penny stocks: Penny stocks come cheaper and therefore are an attractive option for investors to be putting in money.
But you must also remember that a low price means smaller margin and the transaction costs can prove too much for you.
Moreover, studies have also shown that penny stocks are susceptible to fraud and manipulation more than other types of stocks.
One solution to this practice might be to avoid investing in penny stocks altogether as most business sections do not deal in penny stocks.
Even after everything is said and done in case you are willing to put money in penny stocks you need to dig your resources a bit deeper to avail all the necessary information needed to trade in penny stocks.
Holding investment when market is down: Investors generally refrain from investing when the market is down in apprehension that it will go down even more and might result in losses.
But you should understand that market moves in cycles.
A bear phase would eventually give way to bull phase and so on.
Therefore, do not be afraid to invest in a lean market situation.
Leaner times usually present better bargains and instead of following the crowd invest wisely.
Stocks come cheaper during such market conditions and yields more when market rises once more.
Blindly accepting your broker's advice: Brokers are as much human as any other informed investor.
So even brokers might slip in their judgment at times.
Not all brokers are experts.
Moreover, it is not their money that is at stake, the money is yours, so it is always wise to do your own bit of research before investing.
Not updating the portfolio on a regular basis: Some investors do a lot of research before they invest during the initial phase but stop monitoring the funds on a regular basis after that.
This might result in huge losses as you can't afford to let go a single opportunity to earn profit in the world of stock markets.
You have to keep yourself absolutely updated about the prevailing market situations by using the varied tools offered by the brokerage houses to clinch the best possible deals.
Trading too much: Trading too much and too frequently might also be derogatory to the health of your portfolio as in the process you pay more as transaction costs.
Just remember that each trade carries the baggage of tax implications and commission.
So it is better to keep your margin wide and trade less instead of trading more with slim margin.
Trade with consumer bias: Very often the traders tend to invest on products that they have used personally and have liked.
But you should remember that a good product does not necessarily mean a good company.
There is more to a good company than a good product.
Hence a good product might only be a starting point of your research homework.
What you need to look at is the stock performance of that particular company for a few consecutive years.
Hence there are a good many mistakes that any common investor is prone to make in the world of stock market.
No single list would be exhaustive enough.
But the biggest mistake for any market player would be not to learn from the committed mistakes and to be repeating them.