Use artillery yourself. It attacks better than defends.

I use artillery early and often. It's faster, cheaper and more cost effective than light tanks to obtain, but conventional towed artillery is slower than molasses, but then again, so is everything else that isn't an armored car or light tank during the first 5 days . . .

The way to use artillery offensively early in the game is to keep it behind your front-line units, from where it can shell your enemies while taking no losses. The way to deal with enemy artillery defensively is counter-battery fire (use your own artillery against it), or close the distance and attack enemy artillery with your own ground units, ideally from multiple directions at once. In-game artillery can only attack one enemy formation per hour, and if you attack with more than one formation, only one will suffer damage. Exposed artillery is extremely vulnerable, but you need to close the gap quickly and kill it. Dithering within range of the enemy arty while it shells your units is the kiss of death, especially if the enemy has a lot of it.

That said, given the conflicting priorities, low industrial production capacity and scarce resources, I find it difficult to produce more than 6 or 7 arty regiments during the first 5 days of the game. But arty is one vital ingredient in a well-balanced force, and helps to reduce your own casualties by reducing the time it takes to kill enemy units engaged with your own front-line units.