Actually cleaning the carbs isn't the difficult part about cleaning the carbs. It's getting them off and back in the bike that's the problem! if you've never done it before, follow the guide on ninja250.org and be prepared to call your bike all sorts of terrible names. Cleaning the carbs itself is pretty simple, I've never used carb cleaner, just gasoline, my fingers and a shop rag. For cleaning the jets i use a set of gauge pins and push em through, but the right gauge wire from the hardware store would probably work just as well. Be careful with the diaphragms though. They're kinda fragile and i hear expensive to replace. My general rules are don't clean them with metal, and only use gas or carb cleaner. since it's your first time you may want to label parts with tags or something and then compare them to the pics in the guide as you reassemble, and only do one at once so you have a physical reference. It really sucks to get everything back together, look in the bin and think "now where the hell did that come from?"
