Seed confusion

Hi all, want to have a go at making a stockpile of seed for myself for such occasions as now where I fuck up and lose all my plants.
Dumb questions regarding to pollinating for the first time.. will I get some decent plants from crossing a couple of decent F1’s from different strains or do I have to back cross a couple of generations and create IBL’s to try and make a new f1?
It’s a new area for me.. I have been reading the breeders paradise thread but it’s a lot to take in.

Say for eg.. I had two strains.. let’s say blueberry Hashplant and space monkey for arguments sake
Should I
A) cross the two strains as they are?
B) make f2’s of each and hope to find some winners?
C) make f2, f3’s of each and then try crossing them?
D) work one back to F3/F4 and then keep throwing new F1 strains at it and see what sticks?