For those just starting out i found this hugely helpful

Major Points in this Lesson:

Cervical fluid changes throughout the menstrual cycle and is a primary fertility sign.

Cervical fluid is the best sign for learning about the presence of estrogen in your bloodstream.

Cervical fluid is one of the best signs to tell you when you are most fertile before ovulation.

When estrogen is high and you are most fertile, cervical fluid is stretchy and resembles raw egg white.

When you are trying to conceive, it is recommended to have intercourse whenever you observe fertile quality cervical fluid.

Cervical fluid has similar properties to semen and serves similar functions: to support, nourish and transport sperm. 

In a typical menstrual cycle, cervical fluid starts out scant and dry just after menstruation, becoming sticky or pasty, then creamy before the more fertile, watery and egg white fluid is observed when you are most fertile around ovulation. After ovulation, cervical fluid is again scant and dry. 

Ovulation usually occurs around the last day that fertile quality cervical fluid is observed. This is often called the "peak" day.

Here's the website I found it off of! 

http://www.fertilityfriend.com/courses/lesson.php?p=1;5;0;0