Brother, first of all, Welcome to the Forum from Central Virginia!
What James T. said!!! That preservative is not a lube and will gunk up and really make it tougher to clean later on.
Invest in a can of pressurized brake cleaner and some CLP and other cleaning equipment and do it right the first time. Include your mags while you're at it. You'll be happy you did! Expect to use the whole can. Do it outside, and wear eye protection.
There are a few things to check. The gap between the upper and lower halves of the gas block should be even and uniform, left and right. Some Minis (mine included) was very uneven, and that really trashes the accuracy.
If you have some blue loctite, remove the rear sight screws (one at a time) and give them a good treatment with the stuff. Allow some time for the loctite to set.
If your Mini has a flash hider, check to make sure it is tight. Rare, but some had it fall off during initial firing. Makes for both a bad - and embarrassing - day.
Disassembly/reassembly should be done with the hammer cocked, safety on.
Make sure during reassembly that the trigger group is well seated. That may take a slap with the palm of your hand to do it: don't worry, you won't hurt it (the rifle...your hand, maybe).
Clean the bore with the Mini upside down. That will keep CLP from clogging up the gas port. Don't oil the firing pin - it'll just gunk up.
For the newer Minis, make sure the recoil spring guide is correctly oriented (check the manual). Otherwise, you'll get frustrated since it won't work.
Clean it again after firing the first time. Won't need the brake cleaner, just some decent CLP.
