Tackling - Head to which side?

Question
I am old boy starting to play again and have a question about tackling. It has
to do with which side your head goes. I played football and remember being
taught head goes to the side of the ball OR head goes in front of the player to
impede their progress. This usually meant your head was always to the
outside and trying to keep the player "contained". In rugby, I know it is
different but don't really know why. I'm being taught to keep your head to the
inside (scrum side) to push the player outside... opposite of football. Why is
that? Wouldn't it be beneficial to keep the players from getting outside you?  
I've looked for videos and picture diagrams of proper tackling technique and
haven't found anything that references the side of your head. The only video I
found was this... http://www.expertvillage.com/video/2720_advanced-
rugby-howto-tackle-video.htm.  He references "head to the outside" and "not
across the body"... Seems pretty basic and not very helpful to me. I know how
to get someone to the ground but I just want to do it the most effective and
SAFE (for me) way possible. Old bones don't heal as fast.  Any better videos
and/or step by step pics would be cool.

Answer
Hi Kevin, sorry for taking so long to get back to you.

You head should go to the side that is "out of the way". If the player is running at you going to the left you head should go to the right side and vice versa. If the guy is running directly at you it would be best to put you head on the side the guy hold the ball but really don't over think it on that angle. The big thing is to drive your should into the guys guy or lower sternum.

When tackling from the side the rule of thumb is "cheak to cheak" face to butt.

Here is a simple method for improving your tackle. When a player is moving towards you (or vice versa) do not look at their body as a whole, instead focus on the point of center between their hips. Often a coach will tell you to "eyeball" the "string of their shorts". This focus will allow your brain to only register the runner's center of gravity: the "mass" of their torso. No matter what a runner's arms, legs or head does the torso is usually stagnant.

Keep you feet active, stay on your toes either moving towards them or running in place. Close the space between you and the runner swiftly but stay in control. This is to limit the runner's options as much as possible. If you overcommit to running into the tackle the player has a better chance of stepping you.

Focus on the "string of their pants" and drop your center of gravity to set up the hit. Aim the shoulder to that string.

so summarize:

1. keep the feet active "live"
2. focus on the "string of their pants"
3. drive the shoulder through the "string of their pants"
4. wrap the player up and drive with the legs in short steps.

Don't try to pick the player up, this is dangerous and will probably get you penalized. Drive hard with the shoulder and legs