Rely on pre-written patter from magic tricks only if you want to die on stage. "Sure-fire comedy patter" is magic dealer talk for "we wrote a quick lame routine to include with the directions." The only joke is a performer that actually uses those lame lines.
Focus on the comedy. Instead of planning the performance around effects, it must be written around the humor.
Study comedy. Learn from comedians. Do not fall into the trap of imitating other comedians, but learn from the past masters. Old radio performances of vaudeville comedians are a great place to start. These were performers that perfected their craft on the road doing multiple shows every day.
Attempt comedy without magic. A performer that cannot make an audience laugh without magic probably is not going to do much better with magic. Be brutally honest in evaluating this; audiences will be.
Do not force a favorite piece of magic or incredible effect into the routine when it does not add to the comedic value. This is a complete mistake. Comedy magic is about comedy first.
Hire a comedy writer if it is within the show budget. Just as magicians buy magic tricks from magic dealers, there is no shame in purchasing jokes from a comedy dealer.