Often people are forced into avoiding evidence by their commitment to pre-conceived ideas. It can be difficult not to have such ideas but a determination to consider all the evidence is a big step in the right direction. Watch out for redefining words. It can be tempting to do this to make a previous statement correct after all. However, it is probably better to replace rejected statements by more refined versions.
Some bad arguments rely upon poor definitions of words.
Be prepared also to provide detailed explanations. Many ideas collapse under close examination and thus bad debaters will be reluctant to look at them.