swers to navigate iCloud with multiple devices

Hi! I own an iPhone 7, a MacBook Pro, an iPod Touch, and an Apple Watch. I like to have each device for something specific. I like that iCloud allows me to link devices, but it also makes me crazy. I don’t like taking photos on my phone and them ending up on my MacBook that I reserve for work... or downloading an app and it going into my iPod that I only use music for. I do only use one Apple ID. Is this my problem? Iwant certain things separate, but I want things still going to my cloud. Help! I have done some google searches, but none that dumb it down enough for this very specific situation. Thank you!