i think you mentioned the problem yourself. you research sporadically, picking only techs that are quick to complete. ever hear of 'jack of all trades, master of none?'

set up your race with a a few abilities that go well together, and a govt that enhances that build. as for starting techs, i generally get as many engines as i can and then whatever takes me evenly to 0.
in game, instead of researching all the quick stuff, look at what you really get for each tech, i mean think about the direct effect that will have on you, instead of just having a vague idea of what you're upgrading each time. aside from weapons, of course.. they pretty much just get smaller every level and do more dmg every 5 or so.
tbh recently I've been using research as my dump stat and just picking up a little diplomacy, and then getting diplomatic translators real quick and trading for all the techs other civs get and only researching a couple things thye don't cover .. like entertainment. btw whats up with that shit, the other civs dont -ever- get entertainment.
sorry

that bugs me
the thing the other guy said about your military strength is true, too. your military power affects politics bigtime. i generally like to grab laser V from one of the enemy civs after a little bit, cause they always have it. then research a couple levels of miniaturization and slap six or so of em on a small hull. build a couple here and there, checking your "stats and graphs" tab of the civ manager to compare your military strength to other players. as long as you keep it near theirs, you won't be bugged for tribute, and if you keep it above theirs, you get tribute from them

hope that helps
edit-sorry for the wall of text, i've been playing this game single player so long without talking about it .. lol.