When you decide to go for a shot, or play safe, it usually (not always) means you've thrown tactics and percentages to the wind. If you decide to go for a shot, or play safe, is it because it's the tactical and high-percentage thing to do? Or is it more an emotional thing?
With experience, players successfully play by "feel," where instincts built up over years of play tell them when to "go for" a shot and when to play "safe." But those instincts were built up based on tactical probabilities - over those years they instinctively learned when to do each to maximize their chances of winning. For example, they learn when to be aggressive when returning serve, when to play safe, and when and how to mix it up.
But many players simply make the decision to go for shots or play safe. This often happens when a player is nervous and so can't really think clearly. They may mindlessly go for shots or are afraid to play aggressively and so play safe, even if it's not the smart thing to do. Examine your own game and habits - do you do these things at the right times for the right reasons?
To go back to the title of this tip, you shouldn't think of yourself as "going for a shot" or "playing it safe." If you think you have to go for a shot, that implies it's a difficult shot, which is a quick way to get nervous under pressure and miss. If you think you have to play safe, that implies you aren't able to attack effectively, which is also a quick way to get nervous under pressure, especially if you have to attack on some shots. Instead, just think of it as always trying to do the right shot in any particular situation, and the pressure goes away even as the percentages move in your favor. If that means attacking ("going for shots") or pushing ("playing it safe") then so be it - because, in that situation, it was the right shot.