Ranomware, how to I prevent it?

I keep hearing about ransomware. Even the TV show "The Good Wife" featured it in one episode last year! I'm wondering how secure I may or may not be. Here's my set up.
I run my own small business. Two computers synced via OneDrive. Office 365 Business Premium. My machine is a Surface Pro 2 with Bitlocker protecting my SSD. The other is an Acer Aspire laptop. It's there only for occasional use by another person who is logged in also as me. I have Kaspersky Internet Security 16.0. Everything is set to auto update. I have Carbonite which backs up constantly to the cloud. I also have Acronis True Image making a daily back to an external hard drive.
So I think my question is: if I become the victim of a ransomware attack will I be able to access any of my backups? Would I be able to access my OneDrive, Carbonite or external hard drive using another computer?

(In the last 4 or 5 years there have been 6 failed attempts to scam me in some way. One was the I'm in London and I've been mugged, please send me money on Skype chat supposedly from a supplier. Another was where I had initiated a payment to this same supplier and received an email supposedly from him saying to hold the payment and send it to his new bank details. Both of these referred to the same long standing supplier and were about 3 years apart. In both cases he said the problem was at my end which of course it wasn't. In both situations I just phoned him and told him to improve his security. A few days after the second one above he told me one of his other customers had fallen for the "new bank" scam. It was my supplier who lost, not his customer. He had ignored my warnings.) I also know a somebody who fell for the "I've been mugged, send me 2,000.00 euro". I wonder if I'll eventually slip up and get caught some day!