The Sims 3

New to Sims 3, I don't know any of my friends who doesn't like the game. Its definitely one of my favorites. I know plenty cheats but I only use them when I have to, mostly for building houses, barns, etc. 

Money Cheat:
MotherLode - gives 50 000 simoleons, one of my favorite cheats

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Editincas - lets you redecorate your sim+age up, when you are going to redecorate your sim, when you sim turns to an elder and you don't want the sim to die, all you have to do is put the age down to whatever age you want.

Having babies in sims 3

If you want your sim to have a higher chance of having twins or triplets, there is no cheat that I have but you can purhase the fertility treatment of of the lifetime happiness rewards. In order for this to work both mother and father should have it, you must buy it before your sims try for a baby or else it will NOT work.
If you want a higher chance of getting a girl...
Make the MOTHER sim eat plenty watermelon, you can buy this at the grocery store in sunset valley or whatever town you use.
If you want a higher chance of having a boy
Make the MOTHER sim eat plently apples, this is different than the rules of getting a more likely chance of having a girl.
How to tell if your sim is pregnant
Your Mother sim would start running to the toilet. Sometimes but not always, rock a bye baby tune will start playing and that means that your sim wil be pregnant. When it says that your mother is pregnant that is the time to decide whether you want a girl or a boy.

Developing skills

The skills panel will show your Sims levels. You can watch the bars rise as they gain more and more experience. People in the sims 3 can get many skills, I only know the skills from the sims 3 pets pack, high end loft pack and late night, Those are the only ones I can tell what skills they get. Plenty skills can come off of pets to, like for dogs there is hunting and horses there is racing and jumping.
Sims take time to practice their skills, like for art as an example, you have to paint more and more pictures for the sim to get better, you have to be patient about how long it takes you. It depends on how long you let them practice their skills for.
The skill journal
you can press the J key on your keyboard to open your skill journal. You can see how much progress your sim has made on their current skill.

Sims can take time to have more than one skill that they can work on. Though it takes longer to develop the skill you want to finish. It is easier for beginners to work on one skill at a time.