The more melodic a sample you use, the harder it will be to get it to work with other stuff you're already using. Not to mention, if you straight up use a drop from another track, it's not going to stand on its own. You really should work on making your own sounds or at the very least, learn how to truly transform an existing sample. If you use melodic samples, use stems rather than the full mix. That gives you more room to add a personal touch.