Actually, the best thing one can do for investment success may be: nothing. A number of years ago, we used to monitor our investments at least once a week. Then I would add a little here, prune a little there, pull out this weedy asset, turnover that 401k portfolio and put it into another one, etc., all with the intention of capturing the best possible return. It was as satisfying in its way, for awhile, as a more natural gardening hobby. But, I began to notice something peculiar. Our returns were seriously lagging the market averages. In fact, there was an even stranger and more personal comparison possible. A decade or so ago, I set up and then managed a portion of our assets strictly for Val, as befitting her self-employment earnings, which lacked regular 457 or 401k plans. To make sure I was following her wishes for her funds, I frequently asked Valerie for her preferences about trades I proposed making. Invariably the answer came back that she was happy with what she had and not to make any changes. She would always ask if I had been careful when I selected the assets. I assured her that I had, though sometimes the original reasons for purchase were no longer valid or there might have been recent bad news that I felt would lead to the shares soon going way down, etc. She said I should just let well enough alone, then, and assume things would work out well over time. I do not know how she acquired such investment wisdom. Perhaps it was simply intuitive. She had not studied for it, as I imagined that I had. But the upshot soon became rather dramatic. Her portfolio was going up faster than mine (than the assets I controlled in our joint accounts), sometimes much faster.
It turns out that, in general, men tend to invest somewhat more aggressively than women and to trade more often. And, overall, embarrassingly enough, it is the women who have the better investment record.
When I checked back over several of the assets I had bought and later sold for one reason or another (feeling I had gotten a good profit out of them and they were now "fairly valued," or the companies had wound up not being nearly as profitable as I had originally expected, or I simply needed the funds for other hot investments I felt I must purchase right away, etc.), I discovered to my chagrin what should already have been obvious from a comparison of our mutually held assets with those strictly in Val's portfolio: the assets I had sold, once the commission and tax costs of trading had been factored in, were significantly more profitable than the ones I had bought with the proceeds of those sales.
One example in particular comes to mind: With $10,000 I had bought a lot of shares of a number of very small company stocks, including Summit Technology. Once the total value of these shares had gone up to about $15,000, though a few of the holdings had gone down to almost nothing, I figured that I could probably not do better with such risky assets than a 50% return and sold most all of them. After subtracting the commissions of purchases and sales as well as the taxes I paid on these small transactions, my actual return for an average holding period of about two years, was down to roughly 25%, a net gain of about $2500, and that did not even take into account all the time I had spent selecting, planting, weeding, pruning, etc. this "garden" over that two year period.