That's it basically. send freighters either as far as you can to generate more cash or send them to your neighbours to establish good relations.

When the route is established you should see a coloured line, that's the trade route, build an economy starbase so its area of effect overlaps the trade route and add trade modules to the base to increase the income from the route.

Does just one starbase have effect or can I pass a freighter through many starbases area of effect to stack the bonus? That's mainly what I was thinking.

i.e. if the planet is in the area of effect, is it pointless to have a starbase half way down the route?

When you send a freighter to another civs planet, try make sure its far from your planet..the bigger the distance from your planet were your freighter leavs from to the other civs planet the more money you make on that route..if you cant send it far then stick close to home..you may not make as much money but something is better than nothing.

As for econ bases..they do two things.wen you build an econ base near your planet,add modules to it by building constructors..some modules increase the value of your trade routes and any other trade routes that trade with that particular planet of yours were you built the base..research the trade techs first,they will allow you to build modules to attach to your starbase that will increase trade income..

the second thing a econ starbase dose is increse's the productiion of your planets research and maufucturing points..again you have to research factory techs and then attach modules to the star base to increase the production and reserach points on your planet.

Finally,if you can try build a network of econ starbases throught out your territory or at least near your planets that conduct heavy trade,and research ie economy,manufuctruring and research capitols..it makes a huge difference to your economy and your research and your production.

Does just one starbase have effect or can I pass a freighter through many starbases area of effect to stack the bonus? That's mainly what I was thinking. i.e. if the planet is in the area of effect, is it pointless to have a starbase half way down the route?

The trade income is enhanced while the minifreighter is in the starbase's area of effect only. So yes, multiple starbases (with the trade modules) along the trade route would increase the income from the route in those areas. If a minifreighter is in multiple zones simutaneously, I don't know if the increases stack, but I suspect they do.