A Cutter is an awful ship. It drifts like a pig on a sheet of ice. Handles even worse. I can't imagine going back to Cutter with standard thrusters. Shields ( when engineered, and boosted, with an SCB ) are almost impossible to breach, but that isn't the problem. Getting your guns on target is the problem. Even gimbals don't help that much... turrets are useless and have their own issues with friendly fire. It's a freighter.. a big fast freighter. It excels at moving large amounts of stuff from one place to another.. and mining.
As others have suggested, you blew right past the best parts of the game with the smaller ships. A cobra is a JOY to fly. A Python is the workhorse of the entire universe ( 200 tons, medium landing pad, decent weapon placement ) and will do any mission, period. A small ship is a BLAST to fly, the Vulture is my personal favorite. There are tons of other things.. Rares runs and the Road to Riches.. Engineering your ship is a whole journey. But how do you know what to engineer if you haven't really played the game ? Each CMDRs build is custom made for them and their style/tastes.
But, you want a build ?
Just A-rate everything, fill it with boosters except for two point defense units on the back slots. Don't get beam lasers, they will suck a standard power system clean in 5 seconds. I'd suggest burst lasers on the pylons ( fire group one ), and mutli-cannons on the hull mounts ( fire group two ). Make all of them gimbaled, since the convergence is terrible and you'll have issues getting fixed weapons on target. Add a fighter bay, and hire a decent pilot. I'd upgrade the armor as well to military composite, and maybe a few MRE/HRE modules. Don't forget an SCB. That should do for a good basic build. Note that this is for PvE, a PvP'er will rip you to shreds with reverb cascade.
After that...
ENGINEERING : You need the FSD upgraded to level 5, level 5 dirty drive thrusters, and the shield and/or boosters upgraded and adjusted for resistances ( shoot for all to be over 40% ). Power Plant and Power Distributor as well, based on weapon load out. Get one of the multi-cannons modded with corrosive, the special doesn't stack with itself.
POWER PLAY : Prismatic shields are a must.. but that will take 3 weeks. Then engineer those for resistances.
GUARDIANS : FSD booster is a 'must have' item, the other stuff ? Meh, not so much..