וַיְבָרֲכֵם בַּיּוֹם הַהוּא לֵאמוֹר בְּךָ יְבָרֵךְ יִשְׂרָאֵל לֵאמֹר יְשִׂמְךָ אֱלֹהִים כְּאֶפְרַיִם וְכִמְנַשֶּׁה וַיָּשֶׂם אֶת אֶפְרַיִם לִפְנֵי מְנַשֶּׁה
So he blessed them on that day, saying, "With you, Israel will bless, saying, 'May God make you like Ephraim and like Manasseh,' " and he placed Ephraim before Manasseh.
(translation Judaica Press, copied from Chabad.org)
Yaakov blessed his grandchildren, Efraim and Menasheh, that parents should wish for their kids to be like them. However, he doesn't specify in what way we should bless our children to be "like Efraim and Menasheh."
There isn't much discussion of the lives of אפרים and מנשה in Chumash, at least not explicitly. The only thing that comes to mind, at least for me, is what Rashi says (Bereishit 48:1):
ויש אומרים אפרים היה רגיל לפני יעקב בתלמוד
Some say that [the person who notified Yosef about his father's illness was] Efraim, because he was often found in front of Yaakov, in order to learn [Torah] from him.
Spending time learning Torah with your grandfather is a great trait, but I'm not sure if that's the intent of Yaakov's bracha, quoted above; besides for the fact that this is only attributed to Efraim, and not to Menashe (IIRC some would explain that that was the case because Menashe, as the bechor, had to help his father with matters of state) -- this, then, would hardly be a blessing of being similar to "Efraim and Menashe."
So what, specifically, is the blessing of being "like Efraim and Menashe"?