I've read that it goes something like this, you find a perfect female, then a male from a female line that also has charactersitics that you want. You breed these, and you get the F1 generation, which will all have relatively similar characteristics, like brothers and sisters, but they're not twins. However, you don't want to breed these brothers and sisters, because then their offspring will have much more variable characteristics. Expensive seeds will be F1s, so you will be getting the best genetics possible, and while you may be able to create a new strain, you will still never get anything better than F1 per se. If you want to keep creating F1s, then of course you need to keep cloning your chosen femal and male parents to breed the clones and make more F1 seeds. It's my understanding that in order to create a very stable strain and breed for seeds, it may take years to breed and select the right parents.