It comes down to personal preference how you want to try to bond them, but either way you do it it's advised to quarantine the new chin for 30 days (different cage in a different room) before introducing them to your current chin. That allows the new chin time to settle in, for you to start forming a bond with it, and for any illness to show up before exposing your current chin.
Personally I think the best way is slow, so they form a friendship over time. After the 30 days move the cages into the same room and slowly bring them next to each other until they are just a few inches apart and ok being that close together. Then take them out for playtime in a neutral or as neutral as possible area (so it's not claimed territory) for short 5 minutes or so play times. If all goes well then you can increase the time over the next play times until they are ok for a whole play time together, taking dust baths together and eating together you can try them for supervise time in the same cage. During the intro period you can also swap them into each others cages, so chin A in chin B's cage while chin B is in chin A's cage, so they get more use to each other's scent. If at any time during that intro period they fight though it's best to put them back in their own cages and give them a few days to a week to calm down before trying again.
Not all chins get along with all other chins though, so there is no guarantee they will ever be friends. Just like all other humans don't get along with all other humans, the personalities need to mesh for it to work. Also the bonding period can be long, anywhere from days to years, so long as no blood is drawn it's not really a failure yet. Even if they don't get along having another chin around is beneficial though, like having a neighbor vs living all alone in isolation. I have also had chins that enjoyed having a playmate, but didn't want to share a cage with another chin.
