What strategy can I use to solve 6x7 and 3x9?

Well, there are many strategies you can use to solve those problems. You can either use:

1. A Multiplication table

2. A number line

Or

3. Break it down

Example: 8 * 12

What I can do to "break it down" is I can substitute '12' as '10 + 2' and then simply multiply.

(8 * 10) + (8 * 2) = 80 + 16

80 + 16 = 96

So, in this case, 8 * 12 = 96; does this make sense?

You could use multiplication charts and arrays. (there are more)