Variety is the key to eating out a woman. I always try to switch things up and keep her guessing until she is ready to cum. I agree spreading of her pussy gives her a sexy vulnerable feeling (or so I've been told). Here are a some of my tips.
* Spread the area around her clit while licking
* Insert 2 fingers and spread them open for pressure on pussy walls, move in and out slowly - gives her a nice full feeling - vertical or horizontal
* Lick different speeds, pressure and places around and on the clit
* Run your tongue up and down her lips and inside her vagina
* Massage her g-spot with 2 fingers and moderate pressure - a great orgasm trigger
* Keep her clit moist with saliva for lube
* Be creative!
* Take your time it's not a race. Tease her and make it last.
* Talk to her or moan a little. Let her know you love doing it to her.
* Gauge her responses and take her over the edge when she's had enough

* After she orgasms try to extend it as long as she needs. Most women's clit becomes very sensitive after cumming so don't over do it.
* After she cums try putting your palm gently over her pussy so she can ride it for a minute or 2.
A tongue is a very powerful sex organ and it makes intercourse all the better after she has had explosive orgasms as a starter.