Hey Ted, I am going to start taking Vit D3. What do you suggest I take with it to help increase the effectiveness. I have read calcium and I think Magnesium. Would that be correct?

When you increase vitamin d status your body will automatically be better able to absorb calcium, it follows that your need to supplement with calcium will be less.
However the fact that you will now be absorbing more calcium than currently does mean you require a greater amount of magnesium to counterbalance that additional calcium.
So providing your FOOD SOURCES of calcium are around the RDA simply correcting vitamin D insufficiency should be fine. and no more than 600mg/daily of calcium should come from a supplement (I don't supplement with calcium at all and if you are a cheese/milk/yoghurt consumer and have other calcium food sources I doubt you will require supplemental calcium)
However modern foods tend not to have as much magnesium as the equivalent foods had just 50yrs ago. Modern plant breeding, shorter varieties, faster maturing plants generally have lower copper, zinc, magnesium and iron levels. So Whereas 100yrs ago the average adult would have obtained 500mg magnesium daily it's about 150mg/daily now less than half the RDA.
So most people would feel better, sleep better and be better able to deal with stress if they increased magnesium intake.
It is also worth checking what Dr Davis has to say about vitamin k2.

Thank you Ted, very useful post.