I'm probably going to regret this...
How to win the Match as Allies...
From the start prepare to eliminate the MG(s) that set up above the Axis Second and storm a majority of your troops into the apartments, allowing you to flank the center from above. Ensure that 1 MG and 1 Sniper join you in apartments as they will be needed to help push and hold your position. Once the MG(s) at the Axis Second are down, you can rush your few troops from the Allies Second area, allowing a two-pronged attack on the Fountain.
The other Allies Sniper and MG should be around the Allies Second. There are various locations for both to be set up, but the Sniper should stay crouched or standing, not prone, keeping mobility up to respond to enemy snipers/mgs. The MG may or may not set up to watch the sandbags at the corner (not watching the sandbags allows Axis to bypass the MG fire and rush into Apartments.) If this is the case, one Allies assault/support should be left to watch the lower entrance to apartments until the Fountain is secured.
The Sniper who went apartments should aim toward Church Top, Above Axis Second, Top of Archway, Bottom of Archway, V-Crack, Double Windows, preferably in that order of focus.
The Sniper may have to leave the rooftops and head to the bottom floor as some Axis MGs set up in positions to view the Axis Second from the archway, which can not be targeted from the roofs.
This is why it is important to send a sole scout out to try and capture the Axis Second at the same time your Apartment MG sets up in the crack above the Axis Second. Once that is secure, the rest of the troops can rain upon the Fountain from the multitude of angles now at your disposition, with the MG covering the Axis Second, you can focus fire on the Church Top, Archway, and supressing fire on the double-windows.
Once you have control of the Fountain and Axis Second, it comes time to lockdown the Church. Allies troops should move to prevent a rush of troops coming from wine cellar, church, or from the archway. The Sniper in Apartments should focus attention on the church top and the top of the archway (with the archway being the 99% attention). You need to stall for time as the Sniper and MG who were at the Allies second now move up. The MG should set up to stare down the archway as the Sniper proceeds to the Church to help clear out any camping MGs. The Sniper will need grenade cover to allow time to get the shot off without getting killed by an STG before the bullet finds its way to the head of the MGer. With reinforcements being primarily cut off by the sniper watching the archway top, once the MG in church is down its nothing more than a firesale. Tada, you now control Church, Fountain, and Apartments.
Now here comes the tough part...team work. You need to push the top of the archway and wine cellar hard while you have Support troops keep the Axis honest below the archway. You should be able to take the wine cellar in due time, but ensure they you do not overextend yourself. If many of your comrades die, secure the location and prevent the enemy from getting past you until your allies return. Once the wine cellar is taken troops no longer need to be in Church. Yayyy you now control Church, Fountain, Wine Cellar, and Axis Second.
Now comes for the bloodshed part. The Sniper along with the Rocket should focus on turning that corner of the archway to the Axis First along with 2-3 other Allies Support/Assault. 3-4 Support/Assault should hold the wine cellar, leaving the others to rush into the enemy base.
The enemy has two choices with their MGs now, post up at first or watch the wine cellar exit. Posting only one MG at the Axis First will leave it vulnerable to the Sniper/Rocket turning the corner where posting both at the Axis First will leave their rear door vulnerable to a swarm of Assault/Support Allies.
Now comes the toughest part...once the Axis MGs/Snipers are no longer between you and the flag...step on the flag and its going to be a bloodbath as all the Axis Troops start flooding towards you. 1-2 Allies should watch the hallway creating a chokepoint to buy flag cap time. Tada you win!!!
*If you think I missed some kind of detail or something is confusing let me know and i'll do my best to explain.