The basis of playing as a goalkeeper and receiving a high grade is of course successful interventions which let your whole team keep a clean sheet. Basic jumps along the goal line can be performed by pushing the pressing button and choosing the direction.
When the match is about to end soon with an unfavorable result for your team and a corner happens to occur, you should try to take the goalkeeper to the other side of the field and back up the other players in the penalty zone. In order to move your goalkeeper to the other side of the field, play the finesse modifier button, trying to fight for a possible best position for your player. In case of a failed attempt to score a goal, return to your position as fast as possible.
In order to avoid making an easy mistake and remain ready at all times should your enemy try a quick attack, it's worth keeping a ready position just in case. If the goalkeeper is in a proper position, it will be signalled by a round marker appearing when danger occurs - you should follow the game's recommendations as it influences your grade and lets you intervene should you need to.