It really helps to know what kinda of cars do you like (specific model, type or maker) before buying model cars.
Believe me, if you like the car in real life, building the model will be more enjoyable.
Like me, I absolutely worship the FD3S RX7 and thus I have 8 models with different configurations, colors and such. And I'm still looking to buy more.
Just stay away from any models with lots of decals (like Tamiya race cars) for your first few models.