Make sure that you look at the labels on the products you are using.
Fray Check and sewing machine oil are not interchangeable!
Also - if you have several sewing machines - make sure you are using the correct bobbin for that machine!
Test fabrics of unknown fibers before cutting and/or pressing! Some manmade fibers melt when they get too close to a hot iron.
Make sure that the blade on your rotary cutter is 'sheathed' when you put the cutter down. It is such a bother to have to remove blood from fabric and wherever else it dripped.
Some pets really like to get into thread or other sewing things. That usually does not work out well for the pet. (Or your budget after taking pet to the vet.)