Blurry Pictures

The most common reason for blurry pics with a Holga is the bulb switch being incorrectly set. This switch sometimes has a mind of its own and can get switched over to 'B' mode without you realising. You encounter blurry pics when you move the camera while the shutter is open. The best way to avoid this is to put your Holga on something sturdy like a wall or a table while taking your picture. This is less of an issue when using 'N' mode, as the shutter speed is much quicker than humanly possible.

Fishing Nets Flags
Fishing Nets
by squarefrog
Flags
by squarefrog
 

Another reason why your pictures could be blurry is incorrect focusing. This may be a bit more obvious because you'll notice that things either behind or in front of your subject are in focus.