WARNING!: Deploying Artillery Mech is a gamble in the first place, spending money to upgrade them increases the stakes even more. Artillery Mech are very vulnerable to any of the special op bombs, and will likely be killed by a single, well placed/timed bomb.
 
That being said, try to avoid bunching too many together, as in the example in to the right ->
 
Now that we have that out of the way, lets get to why you are here, upgrading your Artillery Mech. First we will look at which countries have which upgrades, and then run thru a suggested upgrade order that should give a very basic idea of how certain upgrades are used, and how they effect gameplay.

It is important for newer players to understand which upgrades to get, and when to get them, to be successful in online play. Keep in mind if you ask 10 different people, you would probably get 10 different answers to this question, so what follows is a general guide which in no way is cast in stone. This guide has been designed to give newer players an idea which upgrades effect arty mech, and how these upgrades apply to the game.
 
Some upgrades effect all vehicles, but several of them only effect certain units. Before you order any performance enhancing upgrades you must first make sure these upgrades will actually effect the troops you have in the field. For example, the Diesel Engines upgrade will not effect the Artillery Mech regiment, as they have no armor units in them. Also, very important that the first thing you do in online play is to deploy a few recon ASAP, to capture as many nearby cities as you can, especially that city in front of your base! Don't worry about upgrades until you have captured and secured those cities!

If the upgrade listed is not available to your country, or does not fit your situation, simply skip to the next upgrade in the list.

When playing as Britian, Japan, or Russia, Military Surplus will generally be your first upgrade in ANY online game, regardless of whay type of build you plan on. Important to get your economy going in the early game!

WARNING!: Not often used for Arty Mech for many reasons. For one, this upgrade is available from the motor pool, which would require you to deploy it first, as well as the artillery brigade. Thats alot of money, and you still have no troops to show for it. It is also rare to make more than six (6) of these as they are very vulnerable to any of the special op bombs

No sense in upgrading your troops until you have produced them... Performance upgrades can be researched as needed, trying to keep pace, or stay ahead of the upgrades of your opponents (you can left click on an enemy to see which upgrades they possess). The upgrades [3] thru [6] below are somewhat interchangeable, and players can choose to research them in the order that best suits their style of play and game situation. Although the Mechanical Reliability upgrade is one of the most beneficial to all vehicles, we have selected it at spot [6] because it requires a motor pool be deployed first (spend your money wisely)

We have to assume that if you are deploying Artillery Mech you plan to use them for what they are best at, Bombarding the enemy from a distance. Any attack speed upgrades offer huge advantages in combat, and allow you to get more rounds down range in less time.

Every country except Germany has the option to upgrade their Artillery Mech with Long Range Artillery. This upgrade will help with one of the best strategies for Arty Mech, Bombarding the enemy from a distance (best from behind the AT Mech of your allies)

Best not to engage the enemy directly with Artillery Mech, but will be necessary at times. Improved Machine Guns will help the Halftrack Units should this occur.

One of the strongest upgrades for all vehicles comes in [6] only because it requires you to deploy the motor pool as well... Making this an expensive upgrade, at a time in the game you should be thinking about getting armored regiments out.

Some of these upgrades may have been researcheed at the infantry stage of the game... or, maybe your team has a chance to win at the mech stage.... If so these upgrades may be for you. If Arty and Heavy Tanks are on the field skip these and get your armor out!!

All regiments will benefit from Foraging, allowing for quicker healing time while in zone of supply. Always get Foraging before Plentiful Ammunition as it costs less and gives a larger bonus. Only available to Japan and Great Britian, this upgrade is often used to upgrade British SaS or Japanese Commandos/Mortars during the infantry stage of the game. Just make sure you research it at some point...

Same deal as Foraging but costs a little more ($100 instead of $75) and offers a smaller bonus (only a +10% bonus instead of +15%)

Available to every country except Russia, this upgrade effects just about every structure and unit in the game. Gives a Bonus of +5 Detection Range for units, and +5 Supply Range for structures that provide a zone of supply. Though the effect may seem small, it does make a difference when laying out supply lines, detecting enemy troop movements, and also helps any regiment that has the bombard ability. Alot of players consider this the last upgrade they get for their arties (late in game), but at only $50 you have a little freedom when you would like to research it.

Usually a late game upgrade since it is researched from the engineer brigade, but may have some applications in the early-to-mid game, depending on style of play.

There is no magic upgrade order that will work in every situation, so be able to adapt your strategies and tactics to keep your gameplay fluid.

"Thus, what is of supreme importance in war is to attack the enemy's strategy."
^{Sun Tzu, the Art of War}
 
"All men can see these tactics whereby I conquer, but what none can see is the strategy out of which victory is evolved."
^{Sun Tzu, the Art of War}