First we must go over a few do's and don'ts.
Always set your Command Center in the center of the build-able square (blue square) and put the Silos around that. If someone destroys either one they will steal a percentage of your total resources. These must be protected at all cost!
Short ranged turrets should not be placed in front of long range turrets and should not be placed on the corners because specters will pick them off.
Find the right distance apart for your resource plants and turrets- to close and your base is pulse tank food but to far apart will not provide enough firepower on one area.
Tec Lab, Staging Areas, Warp, Barracks, and Factory's should be placed outside of everything to help shield whats important. I would recommend placing these within range of your long ranged turrets so they do not get picked off so easy. The idea behind this is for these buildings to draw fire while long range guns pick off the attackers.
~Option 1~The first way is more for the lower level players who do not yet have the option to build as many turrets and have not leveled up their long range turrets to level 5. The higher levels can use this base set up as well.
The idea behind this is to make your resources "look" impenetrable because the barrier of guns surrounding them. This forcing players to battle their way through turrets to take out resources which will generally cost them more then its worth.
It does not have to be set up in a square, in fact you can even make it round. The important thing is one type of building is surrounding the other as shown below.
~Option 2~This way is more for the higher levels because their turrets can reach out beyond the point to where specters can hit the resources plants and outer buildings. The idea behind this is to make the resources look somewhat vulnerable to the untrained eye so it will provoke low levels to attack you. However, the turrets are well within range to pick off anything before they can take out of your resources. mwwhahaha! In fact the units who attack will be drawn in closer to get a shot at your turrets which will bring them in range of even more turrets for maximum destruction.
High levels will have more turrets then they can fit in a single row around their CC and silos and the 4 silos they have will not fill the area around the CC as well. So you can place your short range turrets within the silo area along side the silos and the long ranged turrets around that.
Again this does not have to be set up in a square as shown below.