When you have preparred you fruit or vegetables you need to get as many as you comfortably can into the containers. This may need the assistance of the handle of a a wooden spoon or bottling stick.
It is best if you use slightly damp containers and layer the contents adding syrup or brine as you go. Air may get trapped withing the layers or gaps in the fruit and vegetables, hulled berries and cauliflower florets are good at trapping air. Agitate or give the bottle a gentle shake as you go. Top up the bottle with liquor to cover the fruit or vegetables leaving approx 1cm (1/2 inch) gap at the top then put the lid on.
Clip top lids are designed to release the pressure that builds up during the steralisation process however screw top lids aren't. So tighten screw lids and then loosen slightly when ready to put them in the strealising pan.