-Build 3 SCVs (one for building, 5 for minerals, and 2 for gas)
-Build a Barrack, a Refinery, a Factory, and a Starport
-Make 2 Bunkers for Defense and 8 Marines to put in them
-Add the Add-On to the Starport and the Factory
-Do research on Seige mode and build 2 Dropships and 8 seige tanks
-Put two Seige tanks in each dropship and leave 4 behind for backup
-Send your building SCV to scout and find the cliff nearest to the base NOTE: Make sure that the cliff will be able to see parts of the base
-Drop your seige tanks on the cliff but make sure there drop off with out being seen
-Take your Seige Tanks to the edge of the cliff and put them in Seige Mode, Marines can't attack from below and by the time there Tanks get in seige mode they'll be blown up NOTE: Take an SCV to the cliff and build an Enginering Bay and Build some Missle Turrets for Air Units
-All of the opponents units will be destroyed so you can take in your backups and destroy whatever the other Seige Tanks Didn't get

NOTE: THIS DOESN'T ALWAYS WORK, IT DEPENDS IF ANYTHING AROUND IT OR ON IT IS OCCUPIED, IF IT IS, TOUGH

CreepColony's Opinion: A nice strategy...but watch out for air. Even with missile turrets, a good ammount of air units can take out your tanks. And also, since tanks can shoot further then they can see (in seige mode of course), you might want to spot them with the dropships or the enginering bay.