I actually use quite a large microscope/lupe. It about 6 inches by 2 inches, full hand size basically. I find it a lot better than the smaller ones I had used previously letting me rest a good 2 inches on the desired object. It was still cheap, about 15 quid/dollars/wongas/pounds
Check whether the freebies are are grade one seeds or not, a lot of the freebies aren't top quality. You cannot get quality from crap seeds generally o course so if they do have issues don't necessarily think you are doing something wrong.
Killer strains.. hmmm, such a personal choice. Think about what you like or want from size, length of flowering period, production, type of psychoactive effect, strength of effect, THC or CBD content, smell, taste, and looks and maybe ease of growing and preferred growing environment.