we tried to do a little bit of a seed grow our last grow, but we harvested too early so the seeds are most likly worthless
Let your seeded plant grow until it starts to die on its own. Yes, it takes time and money to go that long but then you will have 100-1000 good mature seeds...Then save most, use some, and clone the shit out of them. If things happen and your grow goes to hell, you still have a but load of seeds to start over.
As stated, you only want the best female plant to be pollinated with the best make plant.
I would only keep seeds from a large plant and not from small or sickly looking ones. I don't have the knowledge to cross breed, but if you have a grow where a male gets loose and does its thing, keep the seeds from the best and largest plant and not the small sick looking ones. If you spot a good size male before it pops, pick a nice looking female and isolate them from your grow and let them do their thing.
Wash up, shower, and change your clothes if you get near an isolated male before ever entering your all female grow area. Pollen can and will hitch a ride on you.