Those sketches are a good start if you’ve never been trained.
Perspective is #1 indeed.
#2 is lighting. Your main light seems to be behind your product and very low, creating this extremely long and heavy drop shadow. This is hardly ever used, only if some special dramatic mood adds to conveying the product’s character.
Usually the main (key) light is at about 45 degrees in front of the product, and 45 degrees up. It gives a drop shadow behind and to the side of the product that is much smaller and more subtle than you’ve drawn it. Also, look into construction of drop shadows, you’re making some errors. And next time do some better hatching like standard cross hatching (angles less than 90 degrees, more like 30), or better, use ink and markers! If you’re creating a heavy drop shadow like you did, you can consider fading it out and blurring the edges the further it moves away from the product. Also make sure to put shading on the product, though I prefer to keep that subtle.