Only two factors impact gravity: mass and size. Alternatively, density and size (since density is mass divided by volume, a measurement of size).
The bigger the mass, the stronger the gravity. This is direct and unavoidable.
The bigger the size for a given mass, the smaller the gravity, since you are farther from the center of mass (the center of the planet). But this is not so important since habitable plantes (those with a solid rocky surface) have quite a reduced span of available densities.
Besides, you can think on external effects. Since your question do not have tags about "hard science" or "fantasy", you can say that there are no external factors (hard science), some natural factors like a dense atmosphere that causes some floating like in water or the rapid spinning Tim B. has proposed in his answer (sci-fi, but note these does not truly changes gravity) or there are magic minerals with antigravity capabilities like Cavorite (fantasy).
Also, gravity pulling from an external body causes variations on gravity (tides), but you can see here on Earth how much you notice them.