The reason why you want to try and make sure that you get the first one in is that that is what your opponent is expecting. Have you noticed how in some games at the first try the opponent might stand behind the baseline? They are preparing for that first shot to cause them trouble, they are giving themselves enough space. However if you ruin the first one then they are going to expect you to do it again and they will move closer so that they can prepare play on the aggressive which is something that you’re going to want to avoid from happening as a beginner to the game.
Some things to keep in mind as a beginner would be the placement that you are going with. Placement is vital, with the correct placement you can cause trouble for your opponent, after a few strokes you will be able to understand which side is their weaker side and which is their stronger and this already will start to give you the advantage.
However, don’t always aim at the weak side of your opponent, if you are consistently going for their weaker side then they will adapt to this and end up putting you on the defensive, you will want to keep it mixed up and mysterious so you keep them from getting used to one area of the court.
Another thing to consider with placement is how deep you are going to put it. The deeper that you go the harder it is going to be for your opponent to attack the ball and it also gives you enough time to get into a good position that will therefore allow you to go and volley the ball and get the point.
Many beginners like to think about just creating a powerful shot which can be deadly for an opponent but chances are as a beginner you won’t be able to control a powerful shot and you may find that you are instead creating more trouble for yourself without any control. The first thing that you want to learn is control and placement and then over time you will want to start learning how to add more power and then move adding more strokes such as the slice and the kick which are going to be great to add to your arsenal of serves.