Knitting using a Boye loom most importantly requires using the proper yarn weight for the loom. Since the pegs are fixed into place, using yarn that is too lightweight makes the project look loose, and using yarn that is too heavy makes the project very dense.
The Boye loom has a slit on the outside of each peg to help keep the yarn in place while knitting. Be sure to account for this when pulling yarn over the peg. Use the loom hook on the outside of the peg to draw the yarn over the slit.
Take the size of the project into account when deciding on a project to make. Various sizes of looms are best suited to different kinds of projects. Find recommendations in the instructions or online for good projects to make with a Boye loom.