My weak spot is high gloss finishes. I can lay down a camo paint scheme, free hand with an airbrush. But I can't get a high quality gloss finish. I follow the guidance of others but I inevitably burn thru. Then because I fear burning thru, I often don't even attempt to sand or polish. And this keeps me out of the car world more than I'd like and doing military and airplanes because the finishes are flat and weathering is good good fun. I would advise anyone to venture out into other types of modeling as you will likely learn some new skills. I've completed a 1/32 F-14, a 1/16 Russian T34, many 1/48 tanks and airplanes/jets of different eras, a USS Constitution (that may get finished one day), Formula 1 models in 1/12 and 1/20 of all eras. Right now, my obsession is drag cars. Another weakness is - I know nothing about engines. I can't even check the oil in my car. So trying to wire everything in an engine proves difficult. But I try to anyway. :/
And I'm happy to see I'm not the only modeler who struggles to finish a model. About 80% thru a project I start to fancy my next project. I have a dozen or more great looking, more than half done projects that I will eventually get back to one day. Maybe. And part of the problem is I've come to feel like I have to have every single aftermarket product that is available for a kit. I blame all you professionals out there for making me dream too highly.