The key is to avoid praising effort when things go wrong. In that case you want to correct behaviour to improve the outcome in similar situations in the future.

However, there will frequently be times when praising effort is appropriate. For example, my son is a competitive road cyclist. All things being equal, the person who trains the most consistently will be more successful in races. So while I give only passing recognition to him for his performance in races, I often praise the effort he puts into his training.