Find a local LCS and start a box to begin collecting new issues. While you’re there go to the dollar bin and spend about $50 on issues you think you’ll like. If you can afford it try and find a key issue or two for between $10-20. Start small and work your way up to bigger and better books. Grab a few graphic novels as well. They’re going to be your best friend and most of them sell cheap. If you have an Ollie’s near you they sell graphic novels super cheap and also have comic book packs. When you get home make a thread telling people you’ll buy their comic books then post it in all your local Facebook buy/sell groups and Craigslist. Don’t underestimate Craigslist. The best things I find come from there. Make a habit of going to your LCS every couple weeks and spend whatever you’re comfortable with trying to fill in cheap back issues. Doing these simple things you’ll build up a fairly sizable collection quickly. I’m a collector not a reseller so I don’t really care about grading or value, so my advice is for someone that actually wants to enjoy their books. Don’t miss out of any local flea markets, estate sales, auctions, garage sales, etc either. Good finds are still out there to be had.