Thanks for the kind comments.
I'm afraid I don't have much in the way of pointers for you, except that your main problem at this point is your lack of perspective - all your drawings look very flat and have no depth. I'm afraid I don't have any easy tips, since I learned about perspective mainly from experimentation and practice. My usual advice is to start practicing perspective with cubes and prisms, simple shapes you can later build up into more complex forms. And keep practicing, that's what's important.
Don't give up because it's not turning out right, figure out what's wrong and find out how to fix it.