>>28328304Using the same lead as a every day pencil is the problem. There's different kinds of pencils that might suit your needs better.
Also if you used the copics on the mixed media, they bleed because it's the wrong kind of paper for them. There is some more resistant paper that works well.
Visit an art store sometime! It's really fun and they're usually really willing to give good info. Since what you use isn't too niche it won't be too hard.