How do i introduce two cats?

I've had my 8 year old cat Levi since he was a kitten. I've been with my boyfriend for almost 5 years, and I recently moved in with him and his roommate about 8 months ago. I left Levi at my mom's house, and my boyfriend's roommate has a cat who is 6 years old. Mine is male and hers is female. I need to bring my cat to live with us now... What is the best way to introduce them?

The best thing to do is set up a sanctuary room for your cat to start with. It should have bed(s), litterbox, water, cat tree/scratcher...everything your cat needs to feel at home. Feliway diffusers throughout can be useful too (assuming the cats respond to Feliway - not all do).

Scent swapping is the first step. Using clean washcloths, thoroughly rub each cat down (one cloth for each cat), paying particular attention to their cheeks - you want to pick up plenty of their 'friendly ' pheromones. Leave your cat's cloth where the other can find it, and vice versa. Don't force the cloths on them, just leave them somewhere obvious. Carefully observe reactions. A bit of hissing/growling isn't unusual at first, but all cats a different. What you want to see is (after they've investigated the cloths) is anything from ignoring/indifference up on the positive side of the scale (ie they might rub themselves against the cloth, purr, headbutt it, lie on it...you get the picture). This stage can even be started before your cat enters the house.

Once they're ok with the cloths, you can introduce site swapping (the other cat goes into Levi's room, and Levi gets the chance to explore the house), and supervised feeding with limited visual exposure (ie either side of a screen door covered with a blanket almost to the floor, or either side of a door cracked open and wedged with two doorstops). Once they're both unconcerned by this, you can gradually increase the visual stimuli until they can properly see each other and are comfortable with it. Ignoring is fine - they don't have to love each other, just accept each other's presence. From this point, they can have supervised meetings until you're happy that they're ok together.

Hope that's clear. These articles may help :-

http://www.thecatsite.com/a/the-ultimate-yet-simplified-guide-to-introducing-cats
http://www.thecatsite.com/a/introducing-cats-to-cats
http://www.thecatsite.com/a/the-multi-cat-household

Thanks a lot @columbine, many good tips. I'll keep you posted. They've kind of been taking turns coming into the "communal area" so far.

I hope all goes well. Remember to let the cats dictate the pace. They'll let you know when they're ready to move to the next step