Best Order to Teach Multiplication Facts:
Easiest: 1's, 2's, 5's, 10's, 11's
Slightly Less Easy: 3's, 4's, 9's, then Doubles(ex. 6x6; 7x7; 8x8)
Hard: 6's, 7's, 8's
You should always start by teaching them the easier multiplication facts first, then go on to the harder facts.
Ways to help students learn multiplication facts:
Make flashcards for them. Start with the easiest facts first. Then a few easy ones mixed in with slightly less easy(majority). Then mix in the hard ones(majority) with barely any easy ones and a little slightly less easy ones. Change up each of the cards as soon as your students have mastered each flashcard.