In between every use:
you can clean your Filter'-it with a pipe cleaner, just pass it several time inside the filter and it will be ready to use again;
any paper also doing the job very well: napkin, toilet paper, rolling paper etc., just cut a little string, twist it and pass it inside the filter like a pipe cleaner.
For a deep clean you have 2 different solutions:
1) Mix in a little pot water and milk (50/50), put the filter inside and put it on a fire source.
Let it boil for 10/15 minutes, then rinse well with water, let it dry few minutes and it will be ready like new!
2) Deep the filter in pure alchool for 5/10 minutes, then rinse it VERY well with water,
let it dry few minutes and it will be ready like new!