When training with the log we always prop it up under plates or a tyre so that we can start with out feet underneath it. We recommend a wide stance, the stance you use for pressing it is usually that best, this way you can pick it up, clean it and press it all using the same stance.
Grab the center of the handles of the log and stand up with it. Sit down into the log and pull into your body. Then use your hip to clean it to your chest. Keeping to log pulled in close to your body and having your back activated is key to a good clean. Without them you will probably clean the bar up above your stomach and then need to use your biceps or shoulders to finish the clean. By making your clean as efficient as possible you can save energy for the press.
Point your knees out slightly so that your knees track over your toes as you dip for leg drive. By moving your knees out when you dip you can keep your body upright. If you move your knees directly forward you will tip slightly forward on the descent and you are then more likely to push the log in front of you rather above your head during the press.
Similarly, with your elbows you want to keep them held high to help you press the log over your head instead of straight up.