Take The Time
You must take the time once a month to review your investment portfolio. It won't take long - less than one hour, maybe 15 minutes.
I don't believe the average working person or business owner should own anything but mutual funds because these are the easiest to buy and evaluate. However, if you do own some stocks the first thing to ask yourself is if each issue is selling for more than you paid for it. If it isn't you must realize this is not where you want to have your money so the best course of action is to sell it NOW and put those funds into some other stock or fund that is going up. You may have a stock you bought 3 years ago and it has risen only 10% or 25% and you can't decide what to do with it - keep it or sell it - because it has been going sideways for a long time. It might go up. It might go down. Call your broker (a discount broker, I hope) and place a 10% good-'til-cancelled (GTC) stop-loss order. Each month review your stop and move it up (never down) if the stock has risen. This way you don't have to think about it and the market itself will tell you when you should be out.
Stops make you money! Brokers almost NEVER recommend stops especially when they want you to buy something. If it goes down they say it is a correction and "it will come back". But when? Remember how they were touting Boston Chicken at $35 and $40 per share? Today it is 50 cents per share.
It is my strong opinion that very few people have the ability to pick winning stocks. I've been trading more than 30 years and I'm right only 50% of the time. Even when I was an exchange member for 17 years and floor trader I would put in a stop as the same time I made the purchase.
If your portfolio is not making a better return than the S&P500 Index you would be better off having your funds in something like the Vanguard Index500 mutual fund. You will then be staying even with the market as a whole.
There are some basic things that move a particular stock. According to a recent study, 49% of the movement of an individual issue is due to the sector in which it resides: technology, financial, automotive, real estate, etc., 31% is due to the general direction of the market itself and only 20% is due to the quality of the company. In other words owning stock in a great company doesn't mean the stock will go up. The whole group must find favor with institutions, banks and pension plan buyers. They move the market.
Easier said than done: you have to be in the right place and at the right time to see your stock go up. That is why you must take the time to review your invests once a month to keep up with any changes that might be necessary.