I just bought this game a few days ago, and I have just been playing it to death with no signs of slowing down. I've died a few times due to trying some risky experiments involving shotguns and kiting enemies, and I've decided to go the route of starting over whenever I die.
I've set up a world where everything is minimum frequency, but maximum size and richness. I have a fairly large "safe" area within which I can build, and I was lucky enough to spawn with coal, copper, iron, and oil within a manageable (but still long) distance of each other.
I'm completely boxed in by super-hives of enemies with dozens of spawners, but they're a good distance away. I just had my first attack earlier today, and I hadn't finished loading up my turrets with ammunition, so they did some damage to the iron mining facility and the conveyor track that brings the ore to the main processing area. My current goal is to ramp up armor-piercing ammunition production, along with improving electricity output so I can upgrade to lasers at some point, since constantly reloading turrets is going to be a pain.
I already have a semi-automated wall production site, which I will be using to fortify with at least a 2 layer thick wall. I may go thicker, in which case I will put the turrets inside the walls so as to allow them to fire at attackers.
Anybody got tips? I have an automated research facility of 7 or so labs with plenty of Red and Green science production to fuel them for the time being. I have an easily edited and expanded factory layout, my only weak point at the moment is defense.