I don’t think there is much on tips or guides, a lot of it is really just chance. Players have made posts with their thoughts and ideas. Give me a second and I can see if I can find them again and link them, 

What have you learned 

There’s another somewhere where players are trying to figure out if horse breeds like certain types of treats

Picture basically means it's Wild Essence, there used to be a bar with it to show how “wild” it is but has since been removed. I think it shows you it may be more harder to catch? I cannot say as I've had horses on a yellow icon run on me but a red icon? I've gotten one no problem.

There really is no set percentage to use what item. Everyone is different but I've come to find out just using sweet treats or crafted treats ((so like alfalfa carrots but without molasses)) works best. I no longer use Petting as that takes energy. I personally never found luck with lassos and whistles nor do I recall what they all do. 

As Maki has said, there is a guide out there on what treats work best for capturing wilds but even using that guide? May not always work out. For example, just the other day I tried to capture a wild thoroughbred, I know their preferred treat, gave him one and on next one? He ran. Sweet treats, if the proper one they like gain 20% bond and you need 75(?)% to get chance to Call them to you but since I give them their preferred Sweet treats, I always get the call at 80% instead and it does not show up at 70%. I believe their non sweet treats but still a favorite? Gains you 10% bond.