New Cat

 You've thought about it, and have decided to take the plunge, and get  furrball to call your own! Wait!! Don't rush in without asking yourself  if a cat is really right for you. Love is not all that goes  into owning a cat, you have to make sure that your lifestyle, and living  arrangement fit into a cats needs.   Before adopting/buying please ask yourself these couple of questions.
1. How often will I be home?
If you said less than 4 than you should consider not owning a cat. If you said more than 6 than you will most likely be alright if you decide to get a kitten.
2. Do I have the energy for a kitten? not applicable if adopting an adult cat.
Kittens require a lot of play, and attention, you should be available to  give them attention, and put up with the constant play + litter box  training.
3. Will I be around for the lifespan of my cat?
The average cat lives 14 years. Will you be able to care for your  kitten/cat for the foreseeable future? Are you going away to college?  Are you planning on moving out of state/country?   This cat depends on you. When you adopted it you made a commitment to stick with it. Should I get an adult cat? Or a kitten?
You always hear online, or from your animal loving friends that you  should "adopt adults! They need you more!" While there is a truth to  this, if you really want a kitten, and will be able to give it the  attention it needs, then I say go for it. Kittens still need somebody to adopt them, you don't always have to be a hero. However, here are some reasons you should consider adopting an adult cat (age >1yr).
 ~ They are calmer. If you want more of a snuggle buddy without the super high energy of a kitten.
 ~ Better mannered. Very likely to be house trained.
 ~ More self-dependent. Can be left alone for longer periods of time without worry. However adult cats can come with some "quirks" you can read this to get an idea of which cat you should/shouldn't take home.  I have pets at home, how do I introduce them safely?
Method 1 for dogs, cats, and larger animals:
Use a clear, glass door, or a baby gate if the former isn't available  where you live. Sit down and place your new cat in your lap. Your dog  (or other larger animal) should be on the otherside. They might touch  noses, or just look at each other cautiously. If one or both of them  show signs of aggression, then that shows you that they shouldn't be  left alone together. If they seem amicable, then you can move on to  method 2. Method 2 for animals of any size:
It is recommended that you try method 1 prior, but if you do not have  access to a see-through barrier then you can skip to this. Before trying  this method it is recommended, but not required to try scent association.
You will need two people for this
Get a friend to hold your dog with a leash, and make sure that they are  strong enough to restrain your dog. Or hold your other cat with their  hands infront of their neck, so they cannot lurch forward or swat. Place  your new cat in your lap, and restrain the same way (less necessary if  you have a kitten). Have your friend ease your dog/cat closer until it  can sniff your cat. If the dog/cat shows any sign of aggression pull it back immediately.  If both of these sessions go smoothly then let your cat, and other animal free, but with close  supervision. Make sure to keep an eye on them for the rest of the day.  If there are no incidents then you can probably leave them alone safely (unless it is a small kitten with a dog marginally bigger than itself!!)