Try to figure out EXACTLY what is causing the problem and find a solution. For example, sometimes all you need to do is increase your scroll rate and patterns that were hard to read become easier. But sometimes that's not the solution, because the problem was not that the notes were just too close together. This solution is much harder to do, and it's hard to find anyone who can help you figure it out, but it's BY FAR the most effective way to improve.
While you're trying to figure out the exact problem, you can also try things like:
Practice maps that are a little bit too hard for you.
Try using a slower scroll rate (on songs that are not too hard) to try to get better at reading more dense patterns.
etc.
There is no trick that can suddenly make you much better at rhythm games. The most effective way to improve is just to keep playing.