For anyone who does (and doesn't have a DS or DS Lite) this guide is for you. This will pretty much speak upon the DS Lite, but you can incorporate some subsitutions with a regular DS, via certain accessories.
Artic White: The First color that the DS Lite has come in, looks sharp and casual.
Onyx (Black): The second line of colors (along with Coral Pink) to come out, looks quite fashionable, but finger prints can be seen easily.
Coral Pink: The DS Lite for female gamers (and male gamers who love the color pink.), the new hip style to pull out of your purse and impress your girlfriends.
All handhelds come with a stylus and charger, for Europe, if you wish to purchase a DS Lite on Ebay, make sure that the charger is the correct version.
Stylus: There are many more styli's out now, especially from third party companies. Nintendo's Official Styli's are too expensive, when you can get the same great quality from other companies, along with an assorted amount of colors, they now even have metal tip styli's, which come in a package of three. I believe the cost of it is $10.99 (USD).
Headphones: If you want to listen to your games soundtrack, you can do so. Buyer beware, buying actual Nintendo Headphones don't have the same quality as headphones such as Sony's or even your regular Ipod Headphones. Save money and use headphones from your MP3 player or CD player. If you do not have one, just get headphones for a good 15 bucks, anything lower than 15 dollars, you're probably going to have low sound.
Cases: Cases are a must if you wish to keep your DS Lite in tip top shape. I recommend a gaming case, with a DS pouch, a game case, 2 styli's a screen guard and a velvet cloth. The average case costs around 20 dollars, and the DS pouch should have a clip in which you can put on your belt. I believe the publisher for this item (that I have is Pelican.). The game case is just so you can have multiple games on you without carrying the cases, as for the screen guard, it's so you won't have any finger prints nor scratches on the screen(s). The velvet cloth is to clean finger prints and smuge off of your handheld, but make sure to do it properly.
Now I'm not going to list any specific games you should get, just the type of genre you might be interested in.
Roleplaying Games- If you enjoy epic quests and a long type of game with deep storylines, this is the game for you.
Platformer- If you enjoy games that require you to climb up obstacles or simple but yet challenging tasks, this is for you.
Simulation- If you enjoy having a realistic type of environment where it's more of real life situations rather than anything else, this is for you.
Fighting- This is for the gamer who just wants to pick something up and go right into the action, the novice fighter is a simple button masher.
Adventure- Similar to platform, but with a compelling storyline and sidequests.
Sports- Self Explanatory.
Racing- For the type of gamer who's always in a rush, and enjoys competing.
Now many games may have a mixture of certain ones, while sometimes it may just be one specific.
ESRB Ratings: Not many DS games are rated M (at least that I know of), and many just go up to T.
E- Everyone, a game everyone can pick up and enjoy.
E+10- A little more comical mischeif and violence, though there's nothing too bad upon these type of games.
T- Stands for Teen, which usually has mild violence and minor vulgarity. Games like these are usually fighting games and sometimes extreme sports.
M- Stands for Mature, in which it usually contains blood, gore, drugs, violence and some sexual content. A prime example would be Mortal Kombat, as well as the Grand Theft Auto series. Games like these are for 17 and up only.
AO- Adults only, game is pretty much close to a porno. There are no specific titles that have this rating, as most of the games that have these ratings are only avaliable in adult stores and black markets.