Fly around the system and find some higher level jobs. Different stations offer different jobs.

You can always go for glory missions. Glory V missions have no cap to their difficulty and can sometimes get downright extreme. If you still want it to be harder, try handicapping yourself. Maybe go in without your favorite weapon, and force yourself to try a new tactic. Some of the most fun I've had in this game has been when I've found myself in a situation where I didn't know how to proceed and had to think outside the box to figure out a way to solve it.

harder missions and weaker characters, try to beat the game faster this way

get a dude with a ghost vow and do his personal thing

the hardest thing in the game is to aim for a top glory score. i think the current world record is a little under 5000, so try catching up.

Top Glory Scores
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=3330106827
Only one over 5000.

Originally posted by Red Rider:

Top Glory Scores
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=3330106827
Only one over 5000.

And 15th world best is well below 4000... You want a challenge, OP ? There you go. Try to make a meme out of it, too, and get an "over 9000 !" score.