Yeah, selling raffle tickets doesn't seem like the most effective way to utilize a raffle. When I think raffle for my own artwork and comic, it more of a way to build hype and grow my reach online rather than looking to make a profit. My thoughts are that profits will eventually come once I find my dedicated audience that's willing to support me.
My last GiveAway/raffle was just this last January, and I used the site Gleam.io to help organize it. I gave away printed comics, downloadable PDFs of comic issues, mini comics, and even a crocheted custom character plushie from the series. And how people entered the giveaway was they'd get an entry for following on FB, Twitter, referring my comic to a friend, subscribing to Tapastic, voting on TWL, multiple entries for being a patreon patron, and visiting the giveaway page daily. This giveaway was a lot of fun for everyone, I had over 1.5k entries to the giveaway, and I gain a lot of new followers and subscribers this way.