Im trying to do a shiny only playthrough but idk how to hunt properly...

Im trying a blind shiny only playthrough. I just beat gym 2 and I got the dex nav. Then I tried to hunt rockruff for about 2 hours but I'm not sure if what im doing is correct. After I get rockruff I wanna go and look for a totodile and a shroodle. How do I hunt for these mons?