Anybody who has written/cracked a cipher can get an easy 10 points here!?

How do you put a space between words while writing a cipher? I have set up a cipher and to start on it you must first find the 3rd letter of every 4th word. My issue is how to put a space between the words written within the cipher. I would put a random letter but i think that after being decoded it would look sloppy and careless. Any ideas? :-) thank you.