There's so much on networking on this site! Highly encourage you to read through the Q&As further :)
I can tell you what works on me as an ex-BCGer: Genuineness.
What doesn't work? Cheesy quartlery emails/LinkedIn emails pretending that they care about me when I know they just ultimately want a referral :)
My view? Networking is NOT about having lots of connections and business cards of people that you barely know. Networking is much more about building deep, lasting connections with people and having a reputation for good quality work. This gets built over time through consistent face time. Get involved in extra cirriculars, work events, clubs, volunteering, etc. From this you'll form deeper connections, which leads to real opportunities.
"Fast" Networking Tactics
Follow these immediate tips:
a) Reach out to people in your network
b) Reach out to people once removed from your network
c) Reach out to people with a similar backgorund to you (i.e. same alma mater, same historically underrepresented demographic i.e. gender, orientation, ethnicity, etc., same career switch, etc.)
d) Tailor a message to them specifically both showing interest in them and their journey and demonstrating that you have done your research and could be a valuable hire
e) Play "tag" across calls you get so that you can work your way towards the company/office/role you want
f) Never directly ask for a referral, but "hint" at needing one (this is nuanced and important...happy to talk through wording)