If your goal is top tier Wall Street investment banking (JPM, Goldman, etc), then the best way is to work a quality finance job for 3-4 years, attend a top to 5-10 MBA program, and try to land a summer internship, which are basically extended job interviews. Unless you graduated with a 3.9+ and did some highly prestigious academic work or internships that you haven't mentioned, it's probably too late for you to jump into the recruiting cycle for undergrad positions. IB candidates start building their resumes for analyst positions 2 years out (internships are everything from what I can tell).
If you're fine with a less prestigious shop, then start applying now + simultaneously study your ass off for IB interview questions. They are mega technical, difficult, and specific, so you'll need to prepare or they'll chew you up. BTW, you'll still need good grades to get an interview at a smaller IB firm (I don't know the exact number but probably 3.6 or 3.7+). I seriously doubt you'll get any interviews if you have a 3.0 and no internships. Still, you don't need the perfect resume than Goldman requires. I've interviewed a few analysts and associates trying to leave smaller IB firms to improve their quality of life, and while their resumes were strong, they weren't crazy. Like, one guy graduated with a 3.2 or 3.3 from University of Wisconsin, got a job at an accounting firm, earned his CPA + a masters of finance with maybe a 3.7 or 3.8, and then got a job as an associate or senior analyst at a mid level IB firm.
Also, Go to wall street oasis or one of those sites. You'll find hundreds of threads and more advice than you can read on this exact question (how do I break into IB if I'm coming from a non target school and have X.X GPA?)
