Hi I did my nea and got a 9 so these tips might help you as well,
First thing :
Make a mindmap of all 4 points and their context.(Do this as your first page of your nea)
E.g Celebrations -definition
What festivals are there across the world?
Christmas,Easter,Chuseok,Onam, Lunar new year ,Eid ,
What symbols or traditions are involved for each 1?
Use these to base around what type of function your product will be.
E.g decoration/storage
Top tip : You don't need to invent a new product you just need to innovate it. This can just be improving a product by adding designs from famous art schools like art deco and combining it with symbols from the festival.
Something made out of wood is good since you can show your skills through various joints.
Look at the existing products and combined features you like e.g for the design,shape , storage ,pattern
Secondly, there are lots of model nea's to look at online. Use their format for your nea.
Thirdly, after you make a design specification which meets your client's needs make sure to have it colour coded so then for each of your slides you can colour-code to show which part of the spec you are meeting per slide.
Have an intro and conc for each slide this will show reflection, intro= is what the slide will be researching conc =how it helped you with your product e.g intro...this slide is to look into the type of joints I may use ...Conc=from researching the joints I found I will use ... because....