I want double spacing between my lines so I used this:
\doublespacing
Now I also want a single double space between my paragraphs, what should I do in that case?
If I didn't change anything in my tex file, I would get a sort of a double double space (4 spaces). I can't tell that for sure, because I do not know how to measure a double space in tex file, but I am giving an approximation. Thus, to cut this short, if I want one double space between my paragraphs, what should I do?

\parskip– StrongBad Feb 01 '16 at 01:47\parskip(and I've misunderstood your question), then don't change it directly. Load parskip if using a standard class, at least. (Other classes may have better options.) This is assuming you are using LaTeX which we can't tell as you've not told us or shown us. – cfr Feb 01 '16 at 02:14