"The peak age for training is from two to seven weeks, but you can really go up to 14 weeks," says Mikkel Becker with VetStreet.com.
Becker says it's important to socialize your kitty. Introduce them to lots of new people and other pets when they are young.
"Because the more socialized your cat is, the more confident and calm they will be around people when you actually want to show off your tricks."
Mikkel recommends clicker training. You make the clicking right as the cat does what you want it to.
Sit is a good command to start with.
"What you can do is as soon as your cat just naturally sits their bottom on a table or on the floor, you want to click and then reward with a treat a second after."
It's almost like you're taking a snapshot of the behavior you want to cat to repeat.
Believe me, they figure it out quickly. I taught my cat, Casey, to sit on command and it didn't take very long.
Remember the pattern: click, pause a second or two, then reward with the treat. Your cat will associate the treat with the clicker sound and doing what you want.
For more information
Simple Cat and Dog Training Technique as Easy as "Click, Treat, Learn"