LNs are one of the kinds of patterns that are relatively easy to practice. If you focus on playing a lot of maps with LNs, you will improve. Of course, there are things you can do to improve your practice too. Pay attention to EXACTLY what patterns you have problems with, then try to find a way to improve them.
Sometimes problems with LNs are trouble with reading them. If you think that's a problem, try different skins, or vision mods like HD and FL. Try lowering your scroll speed, or even speeding it up slightly when playing LN maps.
If it's specifically releases, try focusing on them a bit more when you play. Try to pick out exactly where the release is. Sometimes you can look at an LN and know it's length right away (shorter LNs, or LNs that last exactly 1 measure, for example), for these LNs you can try focusing a bit more on the actual release, since it's easy to figure out how long they last. But some LNs are more difficult to read either because they last for an usual amount of time, or they are affected by SVs, or they follow an instrument that plays a more complex rhythm than the rest of the music, I find that for me the best way to figure these LNs out is to identify what sound in the music they represent and focus on listening to the melody more specifically.
Sometimes the problem is that your fingers seem to get confused when you have a lot of LNs and it feels like you can read it fine but your hands go retarded. As far as I can tell, this has to do with simply not enough practice playing those patterns with LNs. When you have a finger being held down while you have to use the other fingers on your hand to play something, it changes the position of your hands, and your brain has to compensate for that change in position when it needs to move your finger to hit the key. When you don't have enough practice playing LNs sometimes your brain can't quite figure out how to move your finger and you end up making mistakes.