Israel in Gaza, and the United States in Iraq, have both learned, or re-learned, the same tried and true combat rules for urban fighting. These include;
Tanks are a necessity, unless you want to take very high infantry losses (5-7 of your troops for every enemy soldier). The ratio of infantry to armor vehicles should vary from 30 to 100 infantrymen per tank.
The most useful armored vehicle is the D-9 armored bulldozer. This beast is large enough, and powerful enough, to plow through buildings, or to shake buildings to set off booby traps or force civilians (and sometimes fighters) to clear out. You've got to protect the D-9 with infantry, as it is not invulnerable to anti-tank weapons.
It's better to fight at night, as U.S. and Israeli forces have better night fighting equipment and train to use it. This includes the night vision gear on your tanks and armored vehicles. By cutting off the electricity in the enemy held city, you have a significant advantage that should be used.
Grab the high ground, meaning the roofs and top floors of buildings. About all helicopters are good for is to use their guns to clear the enemy off roofs, and to land your troops up there.
Deal with the underground. The sewers will be used by the enemy to move around. You will have to blow up portions of the sewer system. It's not worth the casualties to go down and fight in the sewers.
Snipers are the biggest problem, followed by machine-guns and booby traps. The troops have to learn to stay under cover at all times. And if they smoke at night, don't do it anywhere that an enemy sniper can get a shot at you. Most snipers will be in the upper stories of buildings (but not the roofs where your helicopters can get at them.) A smart foe will booby trap the ground floor entrance and arrange for another escape route, so that if you send troops into the building, the sniper will escape and your guys will run into the trip wires and explosives. The antidote for this is to take the high ground first and use your own snipers to take out the enemy snipers. This is where night operations are essential. The sniper cannot hit what he can't see, and enemy snipers will have a lot fewer clear shots at night. When you do encounter a sniper, take him out with your own snipers, or tank fire, or take the building he's in down with a smart bomb.
Obstacles can work for you. The enemy will try and set up barricades and other obstacles that will lead your troops into a trap. Follow your own plan and plow right through obstacles. You can also use obstacles, especially trenches, to contain the enemy and prevent them from using vehicles to move troops around.
One Israeli experience contradicted American doctrine, which urges troops to advance in the middle of streets to avoid ricochets from walls. The Israelis found that getting shot in the center of the street was more of a danger than ricochets. The U.S. has largely switched to the Israeli method.
Helicopters are very vulnerable unless they keep moving. Even then, they will get hit. You must be careful using helicopters, and use them only at night when possible. Helicopter weapons aren't as useful as you might think. Their machine-guns can't penetrate most walls, and they rarely get off a good shot with their missiles. Choppers are good at keeping the enemy off roof tops.
Intelligence is very important. UAVs are particularly useful because they can observe an area constantly and stay out of range of enemy weapons. SIGINT (listening in on enemy cell phone and radio conversations) is another valuable source of info, but you have to have enough translators familiar with the local dialect. The enemy may also use a lot of code words, which your intel people will have to try and quickly decode, or have the code in advance. It's also possible to get a lot of valuable information from the local civilians. If they are hostile to you (as the Palestinians were to the Israelis), this is difficult, but not impossible. If many of the locals are friendly, you are going to get a lot of life saving information. Use this source of info as much as possible. If the locals are friendly, try and recruit line crossers (people who will go into hostile areas for info.) The enemy will use this ploy, and will make use of kids (usually 10-12 years old, as these are old enough to know what they are doing, and young enough to qualify as children.) The kiddie spies, although usually unarmed, can be particularly deadly, as they are good at what they do and tend to be fearless.
Flashlights are more valuable than you think. Make sure all the troops have them, and a good supply of fresh batteries.
If the battle goes on for more than a few days, sleep becomes a weapon. Trained and disciplined troops are better able to get sufficient sleep to keep the battle going. These troops take turns fighting, and then sleeping. The undisciplined and poorly led enemy does not, or cannot, do this, and the enemy fighters become slower and sloppier because of the fatigue. This is an ancient technique. The Romans, two thousand years ago, trained their troops to engage in close combat for 10-15 minutes, then to fall back and rest, while another line of swordsmen advanced and went at the enemy (who got worn down quickly because they fought until killed, without being relieved by fresh fighters.)