This time is also the perfect opportunity for me to think over my final project and consider topics that I should ( be looking / look ) into more deeply.
Which one is more common ? could you tell me the differences?
thanks in advance
Either one is perfectly valid. I don't know that one is more common than the other, I can imagine people using either variation frequently.
The minor difference is that "be looking" implies that you should be looking now, as well as in the future.
"...I should look into more deeply" gives the impression that you are only referring to the future, and ignoring the present.