If you are factoring by grouping, you want to group the first two terms and the second two terms together in parentheses. When you do this, you always want a + in between the sets of parentheses, meaning you may have to group a negative with a number occasionally.
(xy + 5x) + (2y + 10)
Now that you have grouped, you want to factor out the Greatest Common Factor (GCF) from each group. The GCF in the first group is x and the GCF in the second group is 2.
x(y + 5) + 2(y + 5)
At this point, what you have in parentheses should match, if it doesn't go back and check your GCF again. If it matches, the parentheses is one factor and what is outside of your parentheses is your other factor.