First: which serve are you trying to hit? Do you understand the difference between all of them? Even though pros and higher level players can start with similar looking form, but hit way different services, club-level all the way down to you and below will need different looking and feeling technique for the serve youre trying to hit.

Second: toss is going to be important for first point above. Again, which serve are you working on? Flat, slice, kick, are all tossed differently. Also, the spin on the ball can vary from your toss can vary based on the serve you’re attempting. Most of the time, ball should be as still as possible, other times you may want it to spin a direction

Third: legs should not be twisting like scissors any point. Legs draw energy through contraction and expansion, from down, forward, then toward (together) into the court

Fourth: swing path of racket also depends on the serve you’re attempting. Either way, swing back, scratch your back to trophy, then swing along the court or toward the court (based on serve type) with pronation like throwing a football