Make a cardboard triangle template a little bigger than you want the bunting to be.
Cut out lots of triangles (advise thinking first about layout to get as many as you can out of fabric plus make sure any patterns are the way you want them - I have wasted lots of material before!)
Put triangles right sides together and sew along both long sides (no need to do top as you will sew this later)
Trim the corner/point and turn right side out
Iron
Repeat ad nauseum until you are sick of triangles 
Then get some woven fabric tape - I can't remember its name but I get it from the market, fold it in half along length and iron.
Pin triangles into the fold of the woven tape stuff
Hand sew really loose/long stitches to hold it together and take out pins.
Whizz it through the machine making sure that all the tops of the triangles are stitched into the woven tape. (Do not get complacent or you will have to go back and redo ahem)
Voila. Hang up and admire.
This is only if it might be seen both sides, I think you can just cut fabric triangles and sew to the long woven tape stuff if its going to be against a wall. Not tried that before.
Hope that helps - It is easy, just a bit tedious.