Welcome to the forum!

In my lucid dreams I noticed the color blue was a conspicuous feature on all kinds of prominent objects, from furniture to machinery. I noted it as a dream sign and found that when I saw these oddly-blue objects I could touch them and become lucid, knowing it was significant to me.

As gab said it may take some time to incubate these objects but if you are successful I expect you'll have some great lucid dreams. I find it's always good to start with prominent dream signs you will easily recognize.

Pleasant dreams!