Have her lie down with her legs spread and climb between them. You should be able to look into her eyes while getting your tongue and fingers all the way inside. Putting a couple of pillows under her butt will help you avoid getting a crick in your neck. Make sure none of your weight is on her, and vice versa. Like any good Boy Scout, be prepared.
Many women are worried that the taste or smell of their pussy is offensive.
Put her at ease with kind, sexy words. If she isn't spring fresh, suggest a joint shower. Soap her up and wash her down. Practicality aside, this can be a sexy precursor. Tell her how beautiful she is and make her feel special.