Hello !
I've played for somes years (around 10-12 years maybe), so I'm going to try to give you some tips

(don't hesitate to ask me questions if you want)
My first advice if you are struggling with the game is to use a good player (do not start with the Junior tournaments haha) it will be easier to learn. You can maybe start with a one-year season with an existing player just to get used to playing the game.
If you struggle with your strikes, you can go to the practice mode and play in a very low difficulty so that the IA just throw the ball at you. This way you can try the different strikes and try to find good shot placements.
When I play, I mainly use the lift strikes if i cannot use acceleration. It's more difficult for the IA to put you in a difficult position if you lift your ball and it also gives you more time.
I think that there's no way to see where you're aiming when you serve, it's all about practice. When I serve, I start pressing the direction when the ball comes down and release it just before my player hit the ball. But it depends on your player attributes, the effect you want to put... So you have to practice to learn the best timing for your service.
And if you want to play with your own player, I'd recommend to improve your forehand (or backhand if you prefer). One of your attributes has to be your strengh. If you slowly improve everything, you will be decent at everything but it will be harder to hit winners or to put your opponent in a difficult position. I usually improve my forehand + my velocity at the beginning, and once my forehand is good enough i start improving the rest.
For the rest, it's mainly tactical. Try to improve your court positionning, try to use your opponent weakness, change the way you play according to the surface, ... :p