This guide is a short guide made by a couple of interplanetary veterans who has tried out all build orders and playstyles that are currently in the game. (18th July 2014) The two play styles presented here are the ones one of us has found to be the most effective.
There is the aggressive play style and there is the passive play style. We would recommend that you use the agressive play style in small games (3 players or less) and use the passive play style in bigger games. (4 players or more)
This guide will only help you in the first six turns, since you will have to adapt to the situation as it changes, and we cannot possibly cover every scenario in this guide. so from turn seven on out you will have to judge the situation and decide what to do; Counter spy buildings, spy buildings, lasers, missiles, mass railguns, mass mines or nuclear plants, the possibilities are endless!
Good Luck!

When playing aggressive you wan't to get a few railguns early on, but you don't wan't to screw your economy over. This is how to get some offesive capability early while still maintaining a good economy.

In Turn 1; you should build a solar plant and two mines. They do not have to be placed the same way i've placed them, as long as there is a lot of room and you build everything close together. The tech you would want to pick is Strong AI or Quantum Computing, if you are going for missiles go for qantum computing, and if you are going for shields go for strong AI.

In Turn 2; you should build another mine and a rail gun, in this turnit is possible to build a kinetic defence too, Do Not Build It! Save the minerals instead.

In Turn 3; you should only build two more mines, and fire your railgun. Even if you can't hit, simply firing in the general direction of the enermy will pressure him into building too much defence.

In Turn 4; build a mine, a kinetic defence and a solar plant. Remember to keep fireing.

In Turn 5; keep building mines and fire your railgun. At this point you could build another kinetic defence, this is optional.
Your research should be done, now chose 4th gen. Nuclear Plants.

In Turn 6; you will have enough mines so you should build a Nuclear Plant and two rail guns. It is best if you build these on another continent, or just far away from your mining area. Now chose the Strong Ai/Quantum Computing tech that you din't pick in turn one.

Godd Luck and have fun from here on out.

When playing passive the goal it to lay low and let others fight while you build up your economy and defence.

In Turn 1; build a solar plant and two mines, that is the standard opening for all playstyles. Remember to build it somewhere where there is quite a bit of space. Work you way towards either Strong AI or Quantum Computing in the tech tree.

In Turn 2; you should build three mines. Build them close to everything else you have. Be carefull you only use one connection for every mine.

In Turn 3; keep building mines, and keep the amount of connections used to a minimum. Also if the opponent has gone Aggressive style, and is shooting at you; Don't panic, he can't destroy anything in one shot, and the chance of his planet facing in the right direction, him being within reasonable firing range, there being no planets in the way AND your planet facing in the direction of the shot when it lands is VERY low.

In Turn 4; you should build a kinetic defence (or two if your layout isn't optimal, just make sure most of your stuff is covered) Build mines for the rest of your minerals.

In Turn 5; your economy should be good (1100 or 1200 minerals a turn) Now you should build some rail guns, my advise is to build a solar plant and two railguns on another continent, or just far away, hugging another city. Also you should pick 4th gen. Nuclear Plants as your next tech.

In Turn 6; build two Nuclear plants and fire your railguns. (you can chose to save the energy for defence instead) For tech you should pick the Strong AI or Quantum Computing that you didn't pick in turn one.

Godd Luck and have fun.