Sight words. Love them or hate them, your students have to learn them. Being able to instantly recognize high frequency words not only gives students more confidence in their reading, it also enables them to increasing their speed, fluency, and comprehension.
So what happens when those sight words just won't stick with your students? You provide them with as many opportunities as you can to work with the words. Students can easily become disinterested if a variety of activities are not introduced.