I would like to start of by apologising if this is a common question which has been answered time and time again. I have looked through a few pages of this forum but nothing jumped out at me regarding what I would like to know. Whilst starting a book/story is it a good idea to write random scenes which you have formulated in your head? For example, the main character/s is/are disturbed by an explosion and the sounds of fighting coming from just outside the room. On further inspection it is discovered that the castle, which the current scene is based in, has been invaded by some rather hideous creatures laying waste to the guards. Turning back into the room the character/s walk to a lever of sorts which reveals a secret passageway which is used to make an escape. I would be writing this down in more detail but I don't want to bore you with the long version. I really am new to writing but am wondering if this is a productive use of time. Even if I chose not to use scenes or ideas I write down would it be worth writing them down regardless? If it is worthwhile how much detail should I go into? Should I do the whole scene as though it was going to be part of the book or just just write down a quick description of what is happening and the possible outcome? Any advice will be greatfully received.