Monarch of Evernight maybe? Spoiler: basically the Mc is a human who gets turned into a vampire so he cultivates both powers and there's also a girl who is supposed to be only human but she's cultivating using some demon race cultivation techniques.
Renegade Immortal? (Xian Ni) Spoiler vague summary: slightly further into the story, he found a giant/titan and inherited the cultivation method. He decides to make a clone of himself and will each learn a different technique. At various points of the story they temporarily merge for a temporary boost in power.
Martial God Conqueror he cultivates some one of the demonic birds body tempering technique Perfect World he cultivates a Roc's technique at some point
Your question is too broad. Mc use different race cultivation techniqued Mc is human but can't use humans cultivation technique. Any other descriptions? Like what cultivation does he use and from what race? Any love interest that we could connect to see if its the right novel?
In Dragon Marked War God the MC uses the cultivation technique of the Dragon race, but I know it's probably not what you are looking for. I remember some synopsis with a MC unable to cultivate that chose to do it his way, but I can't remember the title.