Just like the other Arsenal: Demolition maps, team tactics followed by gun tactics will very crucial in your success. Unlike the other Demolition maps, this is a fairly small map thus conflict in any round will be heavily centered around the bank, especially on the roof and the safe.
Since there is only one bombsite within the bank, both teams, the Terrorists and Counter-Terrorists, will focus their attention on the building. As experienced players will know, whoever has controlled the roof will be able to keep out the enemy team from the bank. This will normally allow the detonation or the defusal of the C4 so be sure to keep an eye on the roof. Note that the Terrorist team has the ability to reach the roof faster than the Counter-Terrorists so the map can be slightly unbalanced at some situations.
The C4 can be planted within the safe room but it can also be planted just outside of it.
CTs are typically drawn to this area to flank the Terrorists if the Ts have decided to maintain their position in the bank, especially in early rounds. However, at least one Terrorist could be waiting in the back parking lot of the bank to prevent an ambush from behind. Otherwise, this maneuver can be beneficial to defuse the bomb without having to face the Terrorists at even ground.
If you are wielding the...
Try to eliminate enemy players from a far distance as these rifles are best suited for this situation. If not possible, you can use these weapons for ambushing purposes at close range. Be sure to reload after a fight with a team member is present as these weapons do not have a high clip capacity.
Although the P90 is a submachine gun and does not do a good job in eliminating opponents from far away, armor piercing rounds are your best assistance thus be sure to take advantage of it. While this weapon has an excellent clip capacity and a good rate of fire, the very limited ammo reserve may be a deterrent to you.
Spray bullets at close range but be sure to stick with team members when running low on ammunition and/or need to reload.
The UMP-45 is arguably meant for medium range combat (if a target lacks a rifle), though close ranged fights can also work, if facing a pistol user.
The Bizon can overwhelm a lot of players at close proximity thus try to take users out at long distances.
Avoid close range fights with more than two enemies. The low fire rate and small magazine is pale in comparison to the SMGs and assault rifles that other players may have. Instead, keep at a comfortable distance and try and take potshots at enemies, then duck behind cover. As a CT, the truck can provide good cover to dip in and out of while firing inside of the bank, while T's should take advantage of the chain-link fence behind the bank to try and snipe CT's going for the bank or convenience store.
The Nova is, as to be expected from a shotgun, is useful at close range. However, at longer ranges, the effectiveness will drop sharply. Using the flanks, like the convenience store or pathway near the truck can be extremely helpful, though getting up close and personal in the bank itself is a valid tactic. Just be careful and keep your head down, lest any opportunistic snipers appear and take advantage of your short attack range. However, in the event that you have to attack an opponent at mid range (say, from the front of the bank to the back), you'll find that the Nova is still somewhat effective even at longer ranges, unlike shotguns from some other first person shooter games.
These pistols are considered by some players to be the second best to wield when the Desert Eagle is not available. The Five Seven has great armor piercing rounds but weak damage while the P250 is a good substitute for the Desert Eagle as the weapon has a larger clip capacity but is slightly less accurate. As a final note, be sure to eliminate opponents when they are separated from their team and/or they have suffered heavy damage.
As a CT, it can be dangerous to rush straight into the bank with such a weak weapon. Instead, try to flank around through the convenience store or pathway near the truck and surprise the T's from behind. As a T, the same general rules apply, avoid large and open sightlines, like the front of the bank. Go for the flanks and try to catch the CT's off guard.
Unless the bomb requires a guard or needs to be defused, try to stay away from the inside of the bank and instead, maintain your position from the outside with the SSG 08. The roof is a good choice for snipers but you may be subjected to enemy fire at every angle since there are very limited amounts of cover. Meanwhile, the ground level does not offer snipers sufficient room to escape from assailants but may allow you to provide additional support for your team.
Similar to the SSG-08 tactics mentioned above, try to provide cover for your team members by eliminating enemies from a far distance. Stay away from the inside of the bank, unless the bomb has been planted, and guard any of the entryways to the bank. Picking off opponents should be easy enough for you, if you are familiar with wielding the AWP. Just be aware of how far (or close) you must be away from assailants and you may be victorious in that round.
Just like with the SSG-08 and AWP, it's important to stay away from the inside of the bank. As a CT, stay behind in one of the various buildings or pieces of cover near the CT spawn and try to pick off any T's rushing into the bank, but be sure to keep an eye on the convenience store and the pathway near the truck, as you can easily be flanked. As a T, you can try to pick off CT's through the chain-link fence right in front of the T spawn. Remember that, if you use the roof, you will be exposed from most sides, so be careful.