After following the stock market the past few years, I noticed some interesting evolutions, especially in DAX/DOWJ. People just can't predict the market in any direction in short time, but in the long term we can say there is a bull-or bear market going on or if the market is stagnating for a while. We can see when it startet (after a period of time), but we can't say when market will turn around. So when we realize there are new all time highs, many people think it's too late to invest now and think they missed the 'perfect' moment. 'Market just rose that high, it has to go down near future', that's a widespread reflexion of a lot of people.
I think investing in this period of market situation is way more interesting and 'predictable' (bad word, I know) than people expect. After the market is hitting a new all time high after a long time and hitting the next one constantly over a period of time, we can say there is a bull market going around. Of course, we can't say how long it will last and just realize the situation of a bull market couple of months later, but in this situation stocks are more likely to rise.
So here's the point: If you invest in this period, after doing research about the company you want to buy, it's more likely the stock is going to rise than it's in a bear market. In this way you can 'avoid' (also bad word here) losses because of market direction. More likely the stock is going to rise in market direction in average. There is no exact ending for a 'bull' market (it can last decades). Same thing for selling your stock: if the market is going down for several month and can't recover to old highs, the trend is clearly showing down. Nobody can predict when markt is going to turn around. So that's a 'signal' for selling.
I think you don't have to try to buy stocks at the absolut bottom and sell perfectly, you will make enough money and avoid losses if you buy and sell in market situations you can see the trend is straight going up or down.