First of all, good luck on your long journey towards becoming a breeder
. It is a very demanding tasks that needs a lot of knowledge and research. First you have to buy a good breeding stock that will come from a reputable breeder (that also means traveling a long distance to get it). Good, breeding quality Chihuahuas don't come along that easily.
Next step is finding out whether the puppy you bought is in fact a perfect example of the breed. That you will find out by taking her/him to a dog show where you will also be able to meet and interact with a great number of breeders and other people that will provide even more information.
This is also the place to meet potential studs that will complement your bitch (that means if your female has some not so serious fault - like very fragile or thin legs- you'll get a male with more compact bone structure). Not just the looks, but also studying a pedigree of a stud will be very important. You'll have to study the line of chis your female comes from and the line your stud comes from....... by doing that you and the stud owner will be able to find out whether they are a perfect match..... well, that's in a nut shell
, but i'm sure some breeders on this site will have even more information.
As I said, breeding is a very complicated and delicate matter..... good luck with everything!