How to create CFG for $L := \{x| \#_0(x) \text{ is even and } \#_1(x) \text{ is odd}\}$

Create an CFG for all strings over {0, 1} that have the an even number of 0’s and an odd number of 1’s.

Also, I have a hint HINT: It may be easier to come up with 4 CFGs – even 0’s, even 1’s, odd 0’s odd 1’s, even 0’s odd 1’s, odd 1’s, even 0’s – and combine them …

But I can’t understand how it works

Who can help?