Used car advice

I have a 1999 ("third generation") Toyota 4Runner - more details below.

My question is what improvements should I make that would improve the resale value over what I spend on the improvements?

Who can I ask and get an honest, knowledgeable answer? I figure a body shop has a vested interest in selling me more improvements which may not be cost-effective, while an auto dealer would want to buy it as is and make the improvements themselves to reap the most profit, so they would tell me "there is nothing you can do" or something.

I figure at minimum, the car needs the dents repaired and a new paint job. Would silver, white or black paint be more in demand than the current green? Should I add some popular options that my car did not come with (running boards, roof rack, etc.)?

What about converting 2WD to 4WD?

I live in a border state, so it occurred to me that I might save money by taking it to a body shop in Mexico to have it painted, etc, but I do not speak Spanish and just do not know. It seems too risky for many reasons - any thoughts? I thought there might be an official Toyota body shop down there that I could trust, but have not been able to find it if there is one.

SR5 2WD, 183-hp, 3.4-liter, V-6 engine, regular gas, 19 MPG (combined), fuel-injection, non-interference, four speed automatic w/OD ECT transmission, California emissions, 285,000 miles. Exterior color: "Imperial Jade Mica" (green) with chrome bumpers. Interior color: "Oak" (light brown/tan), cloth upholstery. It has most upgrades, including A/C, cruise control, "power package" (windows, mirrors, antenna, key-less entry, etc.), CD player, six speakers, upgraded Toyota 15" 7JJ aluminum alloy wheels, P235/75R15 tires, ABS brakes, but does not have a roof rack, rear wind deflector, running boards, body-side moldings or fender flares. Paint is badly "sunburned" (turning white) on top and hood, clear coat is peeling in places, and leather steering wheel is also pretty worn. A couple of minor dents and a scratch or two. Well maintained and in excellent working order. Only two owners (family), and have all maintenance records. No smoking, dogs or other bad odors. No accidents, no flood damage, etc.

Also, wondering if there is some way to use the VIN number to obtain a copy of the original window sticker showing the exact configuration (options, etc.) Of the car?

Any advice would be hugely appreciated. Thank you in advance.