What scams or unfair expectations should be known prior to an unsolicited comic book submission?

over the past few years, i've been writing, drawing, inking, lettering, etc. my own comic. i've also compiled a large list of comic publishers that accept unsolicited submissions to send work into. while encountering such a dilemma of questioning the legitimacy and fairness would mean that i would have had to encounter success with a company first. and while these are high-hopes, i'd like to be informed just in case. hypothetically, if i were to reach such a point and get an offer from a comic publisher to have my work published, are there any scams or general pieces of information to keep on the look out for? for example, i'm unaware what would happen with the copyrights to the characters, story, and the book in general and what would be custom in such an industry. also, i've been attending san diego comic-con for nearly a decade now as well as the new york comic-con since it began in 08 or so. i attend a few others as well, but the point of this information would be: i go for my own personal enjoyment and entertainment, but is there any networking or work i can show while there (and specifically for san diego, is there much luck with the portfolio reviews?) i read often that comic companies don't want to be bothered with submissions or art while at conventions. i want to be able to go about this in the most informed way possible so literally any advice on submissions or getting your work noticed would be helpful.