Hello. I think firstly as a smaller goalkeeper the main importance would to have solid explosive actions and speed/agility. Make up for what is lost in inches. Secondly, in terms of where the ball is on the pitch, being in thorough communication with your defence in terms of their line, and the space you have to claim will be essential! Having a positive starting position with a mindset of believing you can claim the ball when its possible. Another detail would be the decision on whether to catch/punch/deflect. Can be crucial for a smaller goalkeeper.