The Sims 3

There are a few milestones for every skill.
Get 2 of the milestones (doesnt matter if its the same skill) and the achievement pops up.

Athletic skill

Bodybuilder: Total hours on the weight bench must be at least 60.
Maraton Runner: Total distance jogged must be at least 500km.
Fitness Nut: Total hours on the treadmill must be at least 75.

Charisma skill

Celebrity: Sim knows at least 25 other Sims.
Personable: Sim knows at least 50 traits of others.
Super Friendly: Sim holds at least 20 friendships simultaneously.
Everybody's Best Friend: Sim holds at least 10 best friendships simultaneously.
Comedian: Sim has told at least 100 jokes.

Cooking skill

Star Chef: Sim has made at least 50 meals.
World-Class Chef: Sim has made at least 75 meals.
Menu Maven: Sim knows all the recipes.

Fishing skill

Amateur Ichthyologist: Achieved when the Sim catches at least one of each type of fish
Commercial Fisherman: Achieved when the Sim catches at least 350 fish.

Gardening skill

Master Planter: Sim has planted at least one of each type of seed.
Botanical Boss: Sim must harvest at least 75 "Perfect"-quality crops.
Master Farmer: Sim must harvest of at least 650 crops of any quality.

Guitar skill

Master Guitarist: Sim has learned every normal song available, which unlocks one more song.
Guitar Star: Sim must play the guitar in at least ten parties and/or commercial lots.
Money Maker: Sim has earned $5000 through guitar playing. Note that this amount is calculated through opportunity rewards and tips, but any amount gained from going to work in the Musician career track doesn't count.

Handiness skill

Electrician: Sim has repaired at least 10 electric objects. (Dishwashers count as an electric object rather than a plumbing object.)
Plumber: Sim has repaired 10 plumbing objects.
Tinkerer: Sim has given at least 10 "unique upgrades" to objects, defined as ten differently named upgrades. That is, upgrading multiple objects with "Unbreakable" still counts as only a single upgrade as it regards to the challenge.

Logic skill

Grand Master: Sim has achieved level 5 of the professional chess circuit.
Celestial Explorer: Sim has discovered 20 celestial bodies.
Teacher Extraordinaire: Sim has given 20 hours of tutoring.
Skill Professor: Sim has given 30 hours of tutoring.

Painting skill

Brushmaster: Sim has painted at least 35 paintings of any subject.
Proficient Painter: Sim has painted at least 6 paintings that are ranked as brilliant- or masterpiece-quality.
Master Painter: Sim has painted at least 5 paintings that are ranked as masterpiece-quality.

Writing skill

Speed Writer: Sim has earned at least $15,000 in total royalties.
Prolific Writer: Sim has written at least 20 books.
Specialist Writer: Sim has written at least 5 books of a single genre.