Yes, you've guessed write ( I hope) - in writing. How? My natural feeling is too jump into a book after a small contemplation of what to write, and just go into it, hammer and nails, not knowing if the plot would work, or not knowing the characters too deeply. I normally just learnt about the characters as I went along. I'm a pantster, and it has it's plus points: excitement of the unknown, spontaneity, lack of rigidity, to name a few. The downsides are obvious: lack of planning leads to writers' block, a messy and an incoherent 1st draft, and a lengthier time writing the 1st draft pitted. The latter plagued my first adventure book, which took me four years.
Now before I say how I counteracted the lengthy writing time, let me put plotting in a nutshell - its the opposite of a pantster and the plotting writer, to varying degrees, plans the book more ( some really plan to the last detail.I.E. Jeffrey Deaver) and has to know the characters and their goals and motives more. Pantsters would call this boring and over methodical and plotters would call pantsters fly by nights, who start fast and then fizzle out cause they don't know their plot inside and out.
As a pantster, I always disliked overly planning, and still do, but I have realised that a little planning makes a more smoother journey, and that's how I wrote my last book's 1st draft within four months. I adopted at least forty percent of the planning method, melded it into my daredevil writing method and voila, I finished the 1st draft in four months. Plotting cuts down delays or the unsureness of writing which contributes to days of not writing, or the writing flowing.
Now I'm not saying you should do the same - if either sides suits you, then fine, but I feel that adopting this method helped me. Likewise, plotters could try being more spontaneous and less OTT in being meticulous.
Whatever it takes to get the job done is the motto.