what he said was true.Unless u have no specific requirement for any specific breed u want. Outcrossing will stable the gene of the guppy but will mess up the strain unless u know what u are doing. In line breeding is safe and easy but will weaken the gene. Mostly guppies bought from lfs arent determinable whether they are F1 , F2 , F3 or F4 and so on. F1-F2 may still be ok but futher on will leads to weak guppies and lots of culls.Overall breeding guppies wasnt really that easy unless u know how it works.That's why lots of F1 guppies are going for high price. To start to have F1 would means Outcrossing.
On out crossing.
Must also determine the gene of the parents.
Dont only look for Pretty guppies
Always look this way before u buy the guppy
Healthy+Pretty
For Males:
Choose those that like to tail other guppies and also very energertic ones.Especially those that like to dart around.
For Females:
Choose those that are quite big body size.Big abdoments(Not bloated one) so they can house alot of fries. And of course don't choose those that enjoy staying at the bottom and doesnt move.This is a sign of weak guppy unless she is pregnant.