If in a dream you append the signature under the document, then in real life you should take the responsibility for a certain offense of which not you are guilty. To see the illegible signature is the sign of the fact that your ill-wishers will try to mislead you. The dream in which you forge someone's signature, means that circumstances will force you to renounce the principles.
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Be sure and keep any other thoughts out of your mind before drifting to sleep as a cluttered mind can decrease the chances that you will remember your dreams upon waking. Also, focusing on remembering your dreams upon waking in the morning is another very important thing. This sounds very easy, but is often hard for some to do. Interpret a dream by "dictionary dream of interpretation"
When you very first wake up, simply think about your dreams. Don't allow your mind to drift off to other things, just lay there and think about the things you dreamt about the night before - dictionary dream meaning.