Use your head; adapting to your opponent is the best part of HS. Personally I write down armies like crazy even though I don't have all the figures to make them.
Killing big heroes really isn't different from killing little ones; they're just bigger, and not susceptible to most instant kill abilities.
Do some reading. Find what people have already written about the units you will be getting; this link is a list of all the figures and their general strategy.
http://www.heroscapers.com/community...ead.php?t=8099
Also please don't type a full sentence in all caps; use bold if you think its necessary, but highlighting an entire paragraph is to much.
EDIT: Also your last option in the poll should be worded, "Get a
balanced mix of figures, and hope for the best
but prepare for the worst"