very good question
engineers are faced with a similar problem all the time
for example, when building a bridge, it's important to try and figure out how to get the maximum load bearing capacity without increasing the possibility of collapse
build a bridge too big, and it's dangerous. build a bridge too small and it's useless. so what's the best size?
in other words: how does one get the most return (upside) with minimal volatility (downside)?
to solve these problems in construction, or chip design, or a million other things - engineers use
linear programming
in the 1930's a stockbroker asked one such engineer how to apply linear programming to trading stocks
the engineer ended up writing a
paper which won him the Nobel prize in economics
the answer to your question: "how to get max upside with min downside?" is in that paper and many
other follow up papers which cover the subject
for less incomprehensible answers consult these
12 ebooks
print them out, read them and you'll have the fundamental understanding necessary for milking the highest risk adjusted returns from listed securities