How to tell where I'm burning oil?

[240sxDann]

So my car is burning oil somewhere, but idk where. Short background, its an s13 with a red top sr20det. Unfortunately I know nothing about the motor. I don't know mileage or anything like that. It's a basic set up, stock motor, 550cc injectors, hks gt25 turbo, and supporting mods. The turbo boosts just fine, and fast. The motor pulls strong as helllll. But, when my oil was checked the other day I was half a quart low, and I keep randomly puffing out blue smoke. Idk exactly what causes it to blow smoke (like if I'm idling or boosting) but it SEEMS as though it happens when I rev down to a slower speed or to a stop. I can see smoke in the rear view, then once I start moving it puffs a cloud then stops. I'm thinking the turbo is going out...but what do I know? lol So any input?