I am growing cucumbers and peppers for the first time ever this year. I need some help figuring out how to know when things are really ripe and ready to be harvested. Issues described below, and photo at the bottom.

Cucumber variety: Bushy
Issue: They never seem to get green. They go from what looks like almost ripe, to yellow. Which, after reading some past posts it sounds like yellow is overripe.

Peppers: Serrano, Poblano, and Green (WI Lakes variety on green, don't recall on others).
Issue: None of these turn a specific color when ripe, so I'm not sure what other guidelines to use for harvest. The green pepper in the pic below has been on the plant at about this same size for a couple of weeks, and no other peppers are developing on that plant, so I finally just harvested it. The serranos I've been picking and using in recipes for the last few weeks, and am noticing the seeds and interior is very compact and there is not a lot of hollow space inside the pepper. So not sure if I am picking them too soon. The poblano I know gets bigger in the store, but didn't want it to get overripe.

Photo: