For the best use of a hoop the stitching fabric must be kept taunt at all times; but often our stitching fabric can slip in the hoop while stitching. To help combat this wrap some bias binding tape around the inner hoop ring. Stitching the ends of the tape on the inside edge of the hoop. This will give your stitching fabric more grip.
Sometimes the project we are going to stitch is small and the fabric we are going to stitch on will not fit in an embroidery hoop. One way of getting around not buying a smaller hoop is to add strips of cotton fabric to the edge of your needlework fabric to extend the overall size to fit in to a hoop.