Writers come in two types but mainly a mix of both. I am definitely a splurger but it can lead me into trouble. I mainly go with my gut feeling for something and see where it leads me. However, a lack of planning means that the structure may fall apart. There has to be some kind of planning even on a flexible scale. And this is me on the whole. Too much planning can be too rigid if you stick to it come what may, and I think it limits creativity.
When I first started writing my planning was minimal and ended up with me dropping stories because I had no idea where they were going - my ideas dried up and stories were shoved into a drawer. Luckily, I never throw anything away (don't let my husband hear that because I accuse him of hording!) and several of these dead end stories have recently been resurrected, one is my first novel, the second is something I am currently working on, now in its third attempt and almost finished.
What changed? Planning. Yes, that word I find hard to use! I have to say the planning was loose but without it I don't think I would ever have finished. I needed to know how my story would end and have some scene ideas on the way to the finish. However, I don't plot out each scene in advance because often I find that my characters guide me. Something happens when I write and ideas spin off from one another. They are like little branches, rooted to the main trunk but offering new and exciting places to visit. These ideas seem to come from nowhere but I suppose as my characters interact things come up that I had never considered before. I love those little quirks and I always go with them. If you stick to rigidly to a plan you might miss that. I really do have to go 'off plan' as I hate being stifled in my writing.
Maybe for others the plan really does work. It can be a safe way to work, knowing every step of your novel is planned from beginning to end. It certainly sounds easier. I'm surprised I don't work this way because I'm a logical person and like to plan things in advance in my own life. I mean, when I go on trips I have the travel plans down to the minute almost. Itineraries are planned in advance, or if not, as soon as I can on arriving! Even so, I am quite a contradiction! I was never a Girl Guide but I am always prepared. When I go to London I always take a map/s, (including a tube map) sometimes guides, camera, a drink and a book! My motto is you never know what might happen and often I might decide to visit several other places in London if I finish the planned one early. Sort of on the spur of the moment (see that? on the spur of the moment - off plan!), yet there is nearly always a loose plan in place. Loose sounds better than vague - vague is a little too scary for me!
The more I write the more I have begun to plan. It really does help with structure to have this loose building block. This leads me neatly into themes. This one came up at one of the masterclasses at Winchester Writers' Festival (as did splurging and planning). I realised that in fact I have done this naturally - the theme bit to create structure. Themes include things like calendars. Writing in diary form (think Adrian Mole and Bridget Jones) or chapters based in different places around the world. You could use pieces of music, different people (for different view points). Looking at some of my stories I have written events over one week and another naming each day as it arrives. Sometimes it helps to do tha,t but of course all stories won't be or need to be written in this way. I found my 'diary' method came when I realised I was getting confused over scenes which meant the reader would to. So I stuck in dates and it has worked.
So, whether you are a spluger or planner it doesn't matter as long as it works for you. You will find the one that you are happy with, but never be afraid to try something new. As for themes - if your story isn't working consider using a theme to hold it together. Which one doesn't matter. Just have a go.