It is not as easy for everybody as it looks. The other day I found a program on tv and I think it was called petfinder.
There was a lady who had lost her cat and the petfinders kept visiting with different cats, but she kept comparing it with her old cat.
Her husband wanted a dog but she did not, anyhow they brought over a nice labrador, but she could not warm up to it, just too big and too active.
So the next time they came over with a little white dog, she did not like white and did not want a dog, but the dog came over to her, while normally dogs never did, and she was so comfortable with the little dog that they kept it and a few months later they said the dog was just perfect for them, something that noone could have predicted.
So don't give up may be you need to search closer to home and may be bring someone with you that can judge personalities etc.