Elizabeth has some great tutorials on painting with both acrylics and oils.
Here’s a great tutorial she has on painting flowers. It was written for acrylic painting, but I think you could easily apply it to oil painting as well:
http://www.elizabethreoch.com/painting-tutorial/painting-flowers-acrylic-art
You can check out some of her other tutorials here:
http://www.elizabethreoch.com/lesson/how-painting-techniques