Improving your offensive moves depends somewhat on your position. However, because the game is shifting to having "do-it-all" players, it is important to be multifaceted in your offensive package. I would break it down into several categories for general offensive improvement.
Offensive moves out of triple threat, offensive moves off of the dribble, and offensive moves with the back to the basket (both perimeter and post). If you don't have a "trainer" so to speak, find players that are effective in all of these areas and study them. Ask a player to "mentor" you. Tell them that you have always admired them and you want to learn some "moves". many will feel honored and want to assist you. But once you learn a move, work to perfect it!
Continue to getter faster and quicker with the moves. Work on staying low on perimeter moves and maintaining balance on back to the basket moves. Most importantly, identify all of the basic moves of basketball. For example in and out, stutter step, crossover, etc. for perimeter and drop steps, pivots,etc. for the post. You will then take the basics and expound on them. But the basics are where you need to start. Finally, you need to use the moves and make them game tested. Nothings worse than cranking up an engine and never putting it in drive.
If you want to be a game breaker, you have to be a practice taker. Only with daily work on your offensive skills will you get better. Get in the habit of not taking shots, but making shots. Most players through elementary to the NBA should make 300-1,000 shots per workout or day. Great players work on a variety of moves which include separation shots off the dribble, separation shots on the finish, separation shots off the catch (triple threat), moving without the ball, and a catch-fake-shoot series. The two most important points in scoring; you must know when to explode, and when to change your speed. The great ones have an explosion game and deception game.
Building up your offensive moves are important to playing the game of basketball. The game is so fast that if you have to think about what move to do the ball will be taken from you before you have a chance to execute it. The key is to work on specific moves at full speed until they get so fast and you actually get bored of working on them. This will ensure that its becoming a habit and something that you will go to instinctively in games. The key is to work on a couple of go to moves. Moves that you are so good at that you know you can go to when you want to get your shot off or create separation. Once you have those go to moves you need to work on counter moves.
The key to offensive moves is being able to choreograph a set of moves based on how bad you beat a player with the first move. For example, you beat a player with a between the legs to the basket the next time you can work on your freeze between for a jump shot. After that you can hit them with a between crossover. It is just like a pitcher in baseball mixing things up and making knowledgeable assessments on what to go with based on how the batter has reacted to previous pitches.