So off topic I missed the Steam Autumn sale last month. I was hoping to pick up Dawnguard. But I heard that their Winter Sale starts on the 21st of December. I was hoping to pick up the 2 DLCs before Dragonborn.

However, I must start of by saying that on my numerous play throughs I have not yet completed the MAIN QUEST. I am just a bit scared about ruining the first entire play through, like skipping certain quests, etc.

Therefore I would like to know what is the best way to go about doing the main quest, civil war quests and Dawnguard?

For example, i'll give you a game like Black Ops 2 that I recently played and they have numerous ways you can go about the campaign with each one resulting in different outcomes at the end. However, there is one perfect route that you can take which tells the best story and resulting in the best outcome, probably the one the developers had in mind.

So I was wondering in what order should I go about completing the Main quest, Civil war quests and Dawnguard?

The Main Quest will have an extra quest If you haven't beaten the CW yet. You should start Dawnguard after the Dragons have appeared.

Saving the main quest and civil war quest for last on my 2nd character. I feel like I spoiled some of the fun with my first character by storming through some of the deeper quest lines to early.

2nd time around on Dawnguard, I'll probably do it around level 50, much like I did with my first character. But that's just preference because I just recently finished it with my first character, and I don't feel like repeating it again so soon.

I'm also attempting to have all the deepest quests reaching there climix at the same times. I think that will give me the feeling, in-game, that all hell's breaking loose and will make the skyrim experience that much more intense, and exciting!