It´s not that hard to start wondering in a dream. You need to ask yourself if its a dream whenever something weird happens in real life. It doesnt need to be something completely unusual, waiting for a bus and the bus isnt coming should be enough for you to make a reality check. Make a habit out of it and always look for odd things.
You´re gonna do that in your dreams as well then.

The next problem will be that you´re probably gonna start finding explanations in your dreams for the weird things and then still dont become lucid. I have that problem A LOT which means I´m not questioning my reality good enough. I´ve changed that (doing multiple reality checks), so I hope I´ll get better results soon.