Many players who want to improve make the mistake of trying to play mostly stronger players. The result is the opponent controls play, and all the player can do is react to the stronger player's shots, or go for wild shots. A player may develop some shots this way, but it'll be hard to develop new shots or to learn how to use them in a game situation.
If you are trying to improve you need to both try out new techniques that you are developing and to try out new tactics. If you do this against a stronger player, you probably won't do so well. He'll probably stop you from doing it, or doing it effectively, and so you won't be able to develop the new techniques and tactics. You won't have any way of knowing if they work, since the stronger player may win the point simply by being a stronger player against something you are just trying out and are not yet comfortable or expert at. Most likely, since these new things won't work against a stronger player, you'll stop using them and so not develop them.
Instead, try out new things against players who are weaker than you. Develop them against these players, in an environment where you can control play a little more (since you are the stronger player), and where you can see if the new things might work. Don't worry about winning or losing – this is practice – as you will undoubtedly lose sometimes when trying out something new, even against a weaker player. (Imagine how bad you'd lose in this case against a stronger player!) When your new techniques begin to work against a weaker player, then it's time to try them out against your peers and stronger players.
Example: suppose you want to develop your loop against backspin. The best way to do this is to serve backspin, and loop the pushed return. A stronger player may flip the serve, push short, quick push to a corner, or push extremely heavy – and you won't be able to develop the shot very well. A weaker player would be more likely to give you a ball that you can loop, which is what you need until the shot is more developed. You need to both develop the shot and your instincts on when to use it, how to follow it up, etc. When you can do it against a weaker player, then it's time to try it out against tougher competition.