Hello Mo,
MAKE SURE THAT YOUR BOOTS FIT WELL YOU BEFORE ANYTHING ELSE!!!
If they're leather then kiwi polish, you don't have to shine them up either, shiny boots make you visible.
If they're synthetic then just brush them off.
Either way to break them in full with HOT WATER, leave 10 mins, put 2 pairs of socks on, pour out water, place boots on feet and wear until dry.
If they're waterproof and loose their waterproof qualities, use Sealskin Long socks (one size bigger than normal shoe size) over your normal socks, they're great.
Enjoy
Rob