Hi, I was in a similar situation. I currently work at a Tier 1. These are the tips I can give you: (1) intern as much as possible (specially if you go to GLC) - I did not utilize my time interning and in hindsight, the experience would have helped me; (2) don't hesitate in cold calling/e-mailing (you never know when you get lucky); (3) make sure you spend time understanding basic concepts with respect to the field of law you choose; and (4) focus on learning as much as possible and from wherever possible (I started my career at a T2 and realized that there is lots of learnings to pick up from juniors to peers to seniors).
All the best, you got this!