The Pele Yoetz (Rabbi Eliezer Papo, 1785–1828, Bulgaria) and the other Ba’aleh Musar bring down that one should always bless God before blessing someone else. For example, when a person blesses his children on Friday night with the classic Beracha of "Yisimcha Elokim…," he should preface the Beracha with "Yitbarach Shemo L’ad" or "Yehi Shem Hashem Mevorach MeAtah V’ad Olam" (God’s name should be eternally blessed). This concept is actually found explicitly in the Zohar Hakadosh.
Another application of this principle is when offering a toast and saying "L’haim" on a glass of wine or liquor. The common practice of saying "L’haim" and then reciting the Beracha is wrong. One should first recite the Beracha to Hashem, take a sip and then wish blessing to his friend.
SUMMARY
One should offer a blessing to Hashem before he blesses someone else.