The "expert level" decks are just showing that it's not a booster pack. That's all that means. Real expert lvel players will have stacks and stacks of cards to make their own decks, so they usually don't need to buy theme decks like those.
Basic tips? I'll put stuff off the top of my head.
1. Each player has 20 life to being with (similar to life points in YGO) and draws seven cards as a starting hand. The first person won't draw.
2. Colors will tell what kind of deck you have. Each color has it's own type of land and their own strategies. I'll list them here:
Colors:
Red: "It's on now!" All-out attacking and raising power to hit for a lot of fast damage.
Green: "Feel the wrath of nature!" Getting a lot of small tokens out, or using creatures to get a lot of mana and pull out big creatures quickly.
Blue: "I own you." Blue lets you counter your opponent's moves and draw cards, so you can keep countering. This keeps them from doing anything.
White: "Can't touch this." White will get increase your life and is good for general defending. It's most famous for it's clerics.
Black: "Wither and die." This is all about destroying the opponents cards by forcing them to sacrifice them, or by forcing them to discard. I've found that black works best when combined with another color.
Lands:
Fire uses mountains for mana. Commonly called "red" cards.
Earth uses forests for mana. Commonly called "green" cards.
Water uses islands for mana. Commonly called "blue" cards.
Light uses plains for mana. Commonly called "white" cards
Dark uses swamps for mana. Commonly called "black" cards.
3. One of the major differences between the games is that you attack the players, not the creatures. From there, the person being attacked will choose to block whatever attacks you make, cast spells to stop them, or do whatever else in reaction.
4. Mana is life. If you have no mana, you can't do anything. Try and get as much mana as you can in the deck, without having too much. A normal balance is two non-lands for every one land (i.e. a spell and creature for every land card).
5. All creatures have something called summoning sickness that they get when they're summoned. This means they can't attack on the turn they come into play, unless they have an effect like haste, which lets them attack on the turn they're summoned.
6. A basic rule of any card game: buy lots of cards. It'll get you more rare and powerful cards.
7. Just have fun with it. It's a game, after all.
