Disclaimer, I haven't played soccer in 15 years, but I've played some and watched a lot :) It is actually pretty hard to miss the box on the penalty kick if yo

Disclaimer, I haven't played soccer in 15 years, but I've played some and watched a lot :) It is actually pretty hard to miss the box on the penalty kick if you are aiming at the box, as opposed to e.g. aiming for the bottom left corner. Then, (given ~equal skill levels) it is pretty much impossible to react to a strong penalty kick and still have time to dive, given the speed and distance - that's why many goalkeepers guess; the stronger the kick, the harder to react. And, as far as I could tell many players have obvious generic "tells" based on how their body, foot etc. align, and especially where they look before and during the run, so that improved guessing. So the best strategy is a strong kick, and deciding the general direction randomly at the last moment. Note how many penalty kicks on the highest levels of play go straight down the middle of the goal, with the goalkeeper diving away from what might seem like an "easy" one to deflect. But if you do something clever and aim, then you are more likely to make the kick weaker, miss, or allow the goalkeeper to guess your plan.