continental is better to learn as a beginner imo. it allows you to throw at the ball and create a good balance of topspin and pace for a consistent serve into the middle of the box with net clearance, i.e. you remove double faults from your game.
i used to lose so many service games due to double faults when i was a novice as i was focused on having a flat serve (i refused to do dink serves). when i switched to a more topspin serve (easy to do with continental grip) i could suddenly play tennis and not lose 2 points a service game due to double faults. as my confidence grew due to the consistency of my serves i gradually added forearm pronation, hitting more through the ball and knee bend to give me more pace.
Disclaimer: I'm NOT a coach...
Real tennis: https://www.youtube.com/watch?v=yDqnkLJ9BtM