You should begin the game by building 7 SCV's and with the 7th you should build a supply depot and then another SCV (the 8th) you should build a barracks. Continue making SCV's and put them on minerals. After the barracks is done build a bunker near by so if a player 6 zergling rushes he can not just run by your bunker. Fill the bunker as soon as possible. Sometimes minerals are further away so it differs when you will have enough money. With the12th SCV make a Refinary. Build 2 more SCV's to put into your refinary.
Build another bunker when you have the extra minerals and fill the bunker. Keep making Supply Depots as you need them and keep making marines until you have 6 extra (Those 6 do not go into the bunkers) Then when u have enough gas (100) and enough minerals (350) make 1 Factory and 1 Barracks. Then pump out tanks and some infantry to provide them with protection.
Once the Factory is done immediately build the machine shop, once you start building the machine shop make sure to save your money, because you need to upgrade to get siege mode and start building a tank immediately after its done. I would suggest to attack with 2 tanks and 12 marines. Make sure to put your marines right in front of your tanks.
This tactic works great against all units. If you attack Protoss and they have a large amount of zealots this may not work. Many expirienced zerg players might have a lurker or 2 ready to wipe out your marines then like 10 lings for tanks. So this is not a be all and end all tactic, however many do fall for it, but you will need a backup plan! And since I do not play mucho money maps that much because they don't require quite as much skill I am not sure if this has the same affect on them all the time! But I am sure CreepColony will gimme a flaw, other than I have mentioned such as if terran has very fast tanks and already has 5 tanks and 4 rines!

CreepColony's Opinion: You should put your marines behind your tanks not in front. I assume the marines are for melee and air units, and since melee units and most air units have a small range, your marines can hit them. Besides, if you put them in front they can get hurt by the splash damage fron the tanks.