as Chess says its complicated, its actually a good idea to save a few nice planets to being with not too many , attack other people constantly and see if they`ve certain patterns to their stacking. Learn from teh ones that kill you, use their stacks, best their stacks build other stacks, its all trial and error.
there are always battle calculators out there, and those are useful tools in the short run to see what gets what, and eventually in the long term to plan a long term high pr build.
in the mid term, and short term though just go ape on everyone, pretty soon they get so tired of wiping you out that they will give you tips, or you`ll see patterns and wipe them out and they`ll either avoid you like the plague or beg you to join their new fed.