IMHO the following are a few tips which will make you greatly appreciate this chemical so much more. In no way am i attempting to tell you what to do. I am merely going to explain what i do to achieve states that i have yet to know anyone (not including people on this site or others) to attain.
Remember, everything said is my own personal opinion, and is not intended to be taken as fact
First, VG's are not the best smoking device. I have used them, they work, but eh. I use a glass bong. This allows you to slowly fill the chamber and take (most) all of it in one big rip.
Second, when you are using only copper screens like that, your crystal is more than likely just going to melt through the bottom one and into your pipe. Also, you should be sure to heat the living hell out of your screens before use
Third, ditch the corncob pipe and go glass no matter what you do, the pipe is burning causing you to cough. Even metal is better.
Fourth, you definitely need to put some herbs under and on top of your crystal. This will both protect the crystal as well as giving it something to absorb into once it has melted (instead of your pipe). ESPECIALLY with a corn cob pipe like you are using. Obtain some damiana leaf or mj leaf or something of your choice and go screen, herb, dmt, herb, screen. The recipe for success
My first pipe i used for dmt was a glass pipe pipe. cheap as hell (10 dollars). The important thing being to cover your crystal well. Not necessarily the gvg or the vg, a nice pipe does just fine imo.
Also, i personally pack about 50-75mg which allows for some absolutely incredulous breakthroughs, though i have been told this is overkill, but hey, to each his own.
Loving vibes and good luck to you!