You want something 1.4 or 1.2 litre. Dont go over, it increases your insurance a crapload and dont go under, the fuel economy on 1.0 and under is crap
Average car does about 10,000 miles a year, so if you find one, work out its mileage a year, if its below 10,000 its a good sign. My cars 2001 and has done 47,000, about 5,000 a year, which is pretty darn good. Lower the mileage the better.
Look for something with service history, indicates its been looked after.
Voltage doesnt matter a damn. if youre refering to the "v" you find sometimes, that refers the amount of valves the engine has, this doesnt matter either.
you want something with long MOT and Tax
Good first cars are vauxhall corsas, fiat puntos and suzuki wagons. Im hankering after a suzuki wagon, their insurance is amazingly cheap.
Suprisingly renault clios, ford fiestas, volkswagon golfs insurance is pretty high, despite their small engine sizes.
Buy from a dealer. Try and spend under your budget and then use the rest to buy a years warranty. first cars never seem to go for long so its good to have them covered.
Regarding insurance, if you go see a car, put a deposit on it and then go to collect it a later date, then you can get insurance for the day of collection. if you buy it the same day you view you will need someone able to drive it home for you. UNLESS you buy from a dealer, they often do free 7 days insurance, but that depends on the dealer. always good to ask when you phone up.
ALWAYS do an insurance quote for the car youre looking at before you phone up or buy or anything.
a helpful tip: on my fiat, thrid party fire and theft insurance was £900+. i had my mum be the registered keeper of the car, and me go on her insurance for it as a named driver. it then cost me £300 lol