I had a dream!! No I'm not about to quote Martin Luther King I really did have a dream and it wasn't concerning human equality but the end of my current Steele novel 'Most Wanted Artefact'. Now I've often discussed the anti-/pro- planning issue and I come down on the side of the Ian Rankins of this world, I sit down and write.
So the end of my 6th Steele novel is approaching, I'm on the last five or six thousand words of the story and thinking about the details of the ending and yesterday I wrote a couple of thousand words in line with the idea in my head. Then I had a dream! The dream was about the ending and is different from what I'd thought, in fact I think that it's better. So now I'm on the horns of a dilemma. Do I write it as I thought or as I dreamt? Of course I could do both and see how it feels but that could be a waste of time.
See how exciting writing without a plan can be!!!!
Charles Dickens biography by Claire Tomalin is very unspecific about the great man's writing habits in the area of planning but there must have been some forethought in his early days when he was writing his books as serials for publication in magazines. On the other hand he had such a hectic life style it would be difficult to add in planning on top of everything else.
If you punch 'how to plan writing a novel' you receive 104 million hits! There is a 'snowflake plan' umpteen versions of '10 steps to ....', '25 ways to plot a story', '5 ways to plot a story' and so on. There are a number of writers who have produced software which purports to teach you how to write a novel and what they are trying to do is sell their software! No surprises there but the bottom line is if you think you may need to plan then there are lots from which to choose. I would suggest you start writing and see what happens.
What you need is an idea!