The last two times I've gotten in to this game I've basically only done trucking. I want to get back into it except this time get good at combat. Are there any good guides on quickly getting started - getting a good ship for combat - and learning effective strategies and tactics? I don't need to learn mechanics from the ground up necessarily.
Depends on what ship you're running now, but from there I can give you a few suggestions. Some may disagree with me on these:
Early game - Viper Mk III - Good early game combat ship,j I used it for quite a while and farmed toward my vulture. It's a small ship, so fast and agile. Has two Class 2, and one Class 1 hardpoint, which is not terrible.
Next step - Vulture - Power plant is it's weakness, but makes up in it's speed, size, and hardpoints being two Class 3. You can get a Class 5 shield, which is nice for a ship of this size.
Ultimate dogfighting ship - Fer-De-Lance - Often considered the end all be all of it's type for the most part (although there are plenty of other viable ships of this style at this tier), has one Class 4 hardpoints and four Class 2. It's a glass cannon, but you have great mobility, especially for a ship of it's size. Boosted and light enough with 4 pips to engines it can break 400. View from cockpit is great, other than the fact that the pilot's seat is off-center and you have this ugly bar in the middle of the screen when facing forward. You have quite a wide viewing angle though.
There's the larger ships such as the Anaconda, but those are kind of a different class, but can still be used for combat.
For weapons, generally thermal weapons are good vs shields, kinetic weapons are good vs hulls/modules. Some weapons are technically both, such as railguns. Often in the early game you'll want to use Beam Lasers to destroy the shields, then aim for the power plant and use multicannons, cannons, or even pulse lasers are viable if you want to not worry about ammo. Honestly though you will probably have plenty of multicannon ammo before having to go back. If your ship isn't an Anaconda or something, don't bother with Turreted weapons. You want fixed or gimballed. Fixed Beam Laser is good just because it's incredibly easy to aim. Gimballed multicannons are also good. Plasma Accelerators are a nice option too.
For your combat modules, you want A grade powerplant, always, A grade FSD is fine, but if you really want to you can go with D. I'll get to why it's okay to keep A FSD, no matter what powerplant soon. D sensors, D Life support (you have more than enough time if your canopy shatters). For Shields you can go wtih C Bi-Weave or A, whichever you prefer. Bi-Weave charges a lot faster, but A is stronger. Regardless of that, you want some shield boosters if you have the available utility mounts. I recommend A shield boosters. Also get a Kill Warrant Scanner, you want D grade. If you want to interdict, get an Interdictor, also D grade, class doesn't really matter. A grade thrusters, always A. A grade power distributor, also always A. You also should look into Shield Cell Banks. For every SCB you have, you should have a corresponding Heat Sink.
For your power management, for the most part it should be 4 pips to systems and 2 to weapons. Systems benefits your shields. If you are not in a vulnerable position, and need the extra power, you can shift to 4 pips to weapons and 2 to systems. If you're trying to keep your target in line of sight, shift to either 4 pips to engines and 2 to systems, or 4 to systems and 2 to engines, depending on if you are vulnerable or not.
You should also set power module priority. Lowest should be stuff you can't possibly use outside of supercruise. This is stuff like Interdictors, etc. Next lowest priority is stuff you can't possibly use when you have your hardpoints deployed. This includes mostly your Frame Shift Drive, it does have a boot time when to turn back on, but you can boost while fleeing and waiting for it to come back on. Next lowest is going to be weapons, Kill Warrant Scanner, and things of that nature. Second to highest will be defensive stuff, shields, chaff, SCBs, shield boosters. And highest will be stuff you absolutely need to go anywhere: Thrusters, Sensors, Life Support, Power Distributor, etc.
Learn to toggle flight assist, and practice it. Once you know how to leverage having Flight Assist off, it's quite useful for catching up with your target.