I learned used the wet on wet technique (Bob Ross or Bill Alexander) of oil painting. I took lessons for 10 years from a student of Bob Ross. So happy clouds and giving each tree a friend was my starting point. I still enjoy that style of painting but have also broadened my approach a bit. A beginner oil painting in this technique can be done in a single 3 hour class.
Advantages of Oils:
Blending colors is easy and beautiful
Oils take a long time to dry so you can blend and change your painting over and over
Mistakes can be "erased" by removing the paint
Disadvantages of Oils:
Oils are typically cleaned with an odorless thinner
Oils themself can have a smell and may be toxic to some extent (gloves provided for those who wish to use them)
Oils take up to two weeks to dry so taking home a painting needs to be done with care
Even with it's disadvantages, oils are still my favorite. I can get soft pastels (which I Love) much easier with oils and skies are much easier for me (which I LOVE).
Neither oils or acrylics come out of clothes easily after they have set so come prepared with a paint shirt or apron.
See below for some of my favorite class samples: