How Do You Properly Use A Side Deck?

[Premier Alexander Romanov]

I honestly don't grasp the concept.
I understand the importance of swapping out cards, but I can never decide what cards to exchange from my Main Deck to my Side Deck.
What if I need those cards I had exchanged, or I screw up the balance?
How do you know what cards can be swapped for others?

[Agro]

Now, STOP.

http://forum.yugiohcardmaker.net/topic/284760-march-2012-format-basic-deck-building-tutorial/

HAMMER TIME.

There's a side deck building tutorial in that thread, written by moi. It also includes information on how you should side in.

[Not-so-Radiant Arin]

Typically, you don't know what you are playing against Round 1, but you do know what you are playing against Round 2. That's a herpaderp, obviously. The reason Side Decks exists is so that you can counter the strategies of that particular Deck. Say if I were facing Dark Worlds Round 2, I would obviously side out my Effect Veilers from the Main Deck, and put in something that cripples Graveyard plays, like Macro or D-Fissure.

Usually, a Side Deck should consist of either Macro or D-Fissure to counter Dark Worlds this format, Maxx C to counter Wind-Ups/Chaos Dragons, Light-Imprisoning Mirror for Worms, Chain Disappearance for Rabbit, and anything else that you might consider to be a top tier Deck. Then, you have room for other possible side combinations, like the third MST, if you run it, Smashing Ground and Raigeki Break for extra removal, and other techs that your Deck runs that you can't fully utilize Round 1. For example, if you're playing Machines that use CyDra, it would only make sense to side in Chimeratech Fortress Round 2.

Your opponent is also thinking about ways to counter your Deck as well, so it works both ways. That's why if you can get the advantage up before your opponent, as far as Side Decking is concerned, you can cripple your opponent in the second game easily. It's a mind game in and of itself.

EDIT: This should probably go in the TCG Section.