Never capture handheld. Always use some sort of steadying device. Tripod, rock, chair... anything, but not handheld.
If you need to zoom, zoom slowly.
If you need to pan, pan slowly.
It is preferable to not zoom or pan.
Capture video under good lighting conditions. Poor lighting causes grainy video. Low end cameras usually means small lens and small imaging chip, so good low light performance is not possible. If this is the case, add light.
Audio also plays a big part of the video experience. There is no single good mic. Different parts of a project may need different types of mics. It also means that the camcorder needs to have a mic jack - and preferably, manual audio gain control.
Since we have not seen your videos or those to which you are comparing, providing specific suggestions on how you can improve yours is impossible.