I usually use a couple of my favorite oils (avocado, olive, camellia, castor, etc.) mixed with conditioner and use the mixture as a pre-shampoo "mask". I like mixing oils with a conditioner because I don't like oils dripping down my neck and face, and the conditioner prevents that. Sometimes, I'll add honey and/or coconut milk to whatever mixture I'm making. I usually pre-treat for about an hour with or without heat. If I'm feeling lazy, I'll leave the mixture in my hear for several hours.
Right now I have the following concoction in my hair: Meadowfoam oil and Camellia oil mixed in a base of V05 Oasis Honey & Almond conditioner.