I want to lower my car, but have a few questions first.

First of all, I'm assuming it's best to get the wheels first.
Secondly, when lowering your car what rim size is best? 18" or 19"?
I just want the car to look more agressive. I don't want it absurdly lower, or anything. I like the way JustinKid's Scion TC looks. That's essentially what I'm wanting to do with my car as well.

 

actually you want to lower the car first so you know where the car sits, then you get the wheels. When you lower the car the offset changes so if you put the wheels on first then lower it, it wont be Flush anymore like you want it.

I recommend you lower it then figure out your specs on the wheels you want and then go for the wheels

 

This would be the best way. I did everything backwards tho. I got wheels, spacers and now I have the Eibach sportline springs in my trunck ready to install this coming weekend.

 

I think 19" wheels is the highest you should go on a mild drop and from what ive seen and read on other threads it seems like the Eibach sportline springs are the way to go! you will also have to consider a wheel with an offset around +35 to have a nice flush look. My aftermarket wheels are +40 so I had to use 15mm spacers front and 20mm spacers rear to poke the wheels out to my liking. Once I drop the car then its gonna feel better than sex!