It's different from the vaginal discharge that's a normal part of your cycle — but you've probably noticed this, because it's a lot slipperier and spreads more easily. So if you're easily excited, or frequently think about sex to the point of becoming a little turned on, you'll probably be naturally more wet.
The qualities of the fluid vary hugely from person to person, and with each person, it can change based of their hormones, emotions — their day, really. If you don't get excited as often or as easily, you may just have to spend a little time in the foreplay stage to get there. First, let me say there's no right amount of wetness to get.
It should also help make the experience more pleasurable for you both.
Vaginal sex works best when both partners are aroused. Foreplay (sometimes called heavy petting) is about getting both people sexually aroused (or turned on) and ready for penetrative sex, through kissing, stroking, caressing, rubbing and touching.
So straight men will have increased blood flow watching straight porn, while gay men respond to gay porn, but not straight porn.