Here's a technique you can use.
Multiply the leading coefficient (6) by the constant (-2).
This gives you -12.
The coefficient of the middle term is -1.
You need a pair of numbers whose product is -12 and whose sum is -1.
After thinking a bit on this, you should come up with the only combination that works, namely -4 and 3.
Now restate your quadratic replacing the middle coefficient with these two.
Now group the first two terms, and then the last two terms.
Factor each group.
is a common factor, so