please help 95 geo prizm lsi

Help i Dont Know a thing about cars . i just bought a Geo przm Lsi for $500 its on 125k miles. i needed a car to get to work so i just bought it with out knowing to much about cars .the cars doesn't have any damages from what i can see . the cars starts to get a bit shaky when i drive around 65 miles and up kinda like it bounces . i have had it for a week . and one time when i tried to start the car a had trouble but i kept turning the key and a couple minutes later it turned on . maybe because it was cold out ?
i just wanted to know if this was a decent buy for 500 ? and what can i do to fix these minor problems. or maybe i can get my money back from my friend and buy something else ?

Try somthing simple like making sure the tires are properly aired up. If that does worked check to see if the tires are balanced. The car probably needs to be tuned up. Go ahead and change the plugs, wires, and filters. This pretty easy to do. While you are at it change the oil and transmission fluid. The cars are bullet proof, I have 220k on mine and it has been the best car I have ever owned.

Hey guys same things happened with me too my rover always give a bit problem in winters while starting also in snow it really need sometime to start