Here's a helpful step-by-step guide: How to clean rusty tools. You have some fairly heavy corrosion on the nippers, so I'd suggest starting with 240-grit sandpaper to remove the bulk before moving on to steel wool.
It's really important to apply an oil to the tools after cleaning as they'll start to rust again almost immediately. WD-40 or even a cooking oil will do.
Please let me know if you have any questions.
Thank you everyone for your suggestions. I went with vinegar and salt, soaked overnight, scrubbed with a wire brush and repeated. Wiped all the black off, washed and a good spray of wd40 to finish. Like I say, they're not perfect but neither am I. Happy with the end result though. Now if I could just remember to bring my tools in lol
Great work @Jeanagh! Thanks to your efforts, I'm sure you'll see many years of service out of those tools.
Many thanks for sharing your results.