For those who have gotten past learning the Rules of the Game, here are some tips for you when you're constructing a Deck and using it:
1. Decide on your Deck- What this means is that before you make a Deck, decide on what kind of Deck you want to use, for each Deck has a different playstyle, For Example:
-Blackwings are a Aggresive Deck, focused on overwhelming your Opponent with Superior Swarming, Power/Control Cards and Effects.
-An Exodia Deck is the opposite, focusing on Drawing and Defending against your opponent's moves until you gather the 5 Cards in your hand so you can win.
2. Research- Once you've choosen a Deck, do some research on your Deck. A good site for this is YugiohWiki, due to its massive amount of information (note: Using YugiohWiki to HELP make your Deck is not Netdecking, look it up on YugiohWiki and see for yourself ). Anyways, By researching on your Deck, you can learn what Cards and Strategies your Deck is capable of using.
3. Decide your Strategy- Most Decks can be built to use different Strategies, so its up to You to determine your Deck's Tactics and any backup plans you may have in it. When you've decided on a Strategy, make sure you put in Cards that support and Execute THAT strategy.
4. Testing- This simply means to use your new Deck in some Duels, in order to evaluate how well it performs, and make mods when you see flaws in its Performance, or if the Meta is giving your Deck Trouble.
Some Last-minute Tips:
-When you're Dueling, make sure you follow your Strategy(s) according to plan
-When making your Deck, try to keep it as Close to 40 cards as possible, but dont get rid of too many key cards to get it to 40, some Decks do better with more than 40 cards.
-Don't be afraid to accept some help from Your Fellow Duelists, After all, It's a game, not a War.
-Finally, HAVE FUN DUELING!!!