There are three tenets to combat that I follow. This applies to ALL ships. No matter how big and slow it is, the way you play the ship is exactly the same. Larger ships are just a bigger sidewinder.
1: Avoid damage as much as possible.
2: Mitigate damage as much as possible.
3: Eliminate sources of damage as fast as possible.
These are not listed in an order of priority but serve as three rules you should follow under most contexts. A small breakdown of the three is as follows.
Avoiding damage is obvious. You want to always be out of the enemy's firing arc as much as possible. With boosting (and you should be boosting), you can easily position to the side of most enemies, even for a very brief second.
Mitigating damage. This one is most detailed but it boils down to
pip management. A big ship cannot fully evade smaller ships. They're going to have to take damage at some point. If you get hit with a railgun, your first instinct should be to throw all pips to shield if you can see your enemy and aren't actively evading them. With NPCs, they're almost certain to nail the next shot against you. 4 pips to shields gives you ~68% damage resistance, *multiplicative* on top of your base resistances (engineered or otherwise.) Likewise, if you're trying to boost around an enemy to get out of damage, you might have to throw a pip to shielding to sponge up an incoming Plasma Accelerator shot, but only for a second to absorb the damage before turning the rest of the pips to engine to recharge your boost and increase your maneuverability again. In short, you have to be throwing around your pips constantly, because active pip management is what makes the combat boring and hard into an actually engaging exercise of skill and management.
Eliminating or removing sources of damage should be obvious. Say you're flying a vulture. You have two large hardpoints, say two burst lasers. You see a wing composed of an eagle and a gunship. Which do you take out first?
If you said Gunship, you're wrong. If you remember the tenets of earlier, you should be avoiding as much damage as possible while mitigating it as much as possible. That means kiting the gunship. But you
cannot kite more than one ship at a time. Even if you perfectly kite the gunship, that eagle is going to wear down your vulture's shields, and your vulture's dual bursts are going to have a hard time breaking through the hull of the gunship, even if you target the powerplant.
The correct answer is the eagle, because with Tenet 2 (Mitigating damage) you should have enough damage to burst down the eagle while throwing some pips to shield to reduce the gunship's incredible firepower for a brief moment. After the eagle is down, you can easily kite the gunship and circle around it and eventually snipe its powerplant with the burst lasers.
Something unstated but should be obvious is that
your angle of attack against enemy hull is extremely important. Hitting an enemy from the front means they have a much smaller profile and will take much less damage. Multicannons seem to have a chance to be deflected if striking from a bad angle. However, shooting
perpendicular to your enemy hull seems to increase damage. I believe it's because the angle of attack allows for more hits on target AND because it simply makes sense for FDev to have this level of detail given how inconsistent damage is against hull at times. That and it literally just makes sense, because it's why armor on modern military vehicles is angled, so as to deflect the energy of any incoming blow. This just coincides with the avoiding damage and mitigating damage, because if you're outside your enemy's firing arc, you should be facing them at an exposed angle where they'll be exposed to significant damage.
As an example video, this is a solo wing assassinate (pre 3.1) demonstrating two of the tenets.
https://www.youtube.com/watch?v=yhoe89WYc3Y&feature=youtu.be Using a thrustmaster X.
Here I'm avoiding as much damage as possible (the wing assassinate target) because the main mission target has engineered weapons. However, the 5 expert ranked allies do not have engineering and no absolute damage nor railguns (save for one security force) so my shields can take most of the damage. This brings me to the mitigation aspect where I am actively managing my pips to maneuver around my target as fast as possible while dedicating 4 pips to shielding when absorbing the wing's constant firepower. Here I am ignoring the "eliminate sources of damage as fast as possible" because it's simply faster to kill the big ship than to focus on all 5 wing ships while absorbing damage from each and every one, which includes the mission target. Hence, why it loops back around to tenet 1: avoiding as much damage as possible.
Tl;dr, just play actively and don't sit in front of an enemy and hold down the trigger. What's your natural response to suddenly having an Anaconda turn the guns onto your federal assault ship? It should be
get out out of the bloody way. All this "tenet" nonsense I'm rambling about is literally nothing more than the result of me just naturally playing the game. There really wasn't any rhyme or reason to why or how I played, but this is about as on paper as it gets.
Your alternative is to buy an Anaconda, put multicannons on it, and hold down the trigger with no maneuvering with all the Shield Boosters and SCBs you can afford to put on it. But that's not fun.