Things you probably shouldn't do.
Ask for a discount.
Nope. This isn't Pawn Stars and I'm not selling junk for my mama's basement. When you say "Can I have a discount?" I hear "I'm a cheap SOB and I don't want to pay what your services are worth." My response is that of a cantankerous old fart who has just been insulted and more than likely your email address goes into my spam folder never to be seen again which leaves you wondering why there isn't any more replies from me. I'm not dead. I'm pissed.
Don't know what you want but contact me anyway. I don't read minds. Never been good at it. I can give you my ex-wife's phone number if you don't believe me. If you don't know what you want, I sure as heck don't. At least have an idea of what you want. If you have problems explaining it or getting the idea across... perhaps practice on others around you. I'm pretty good at English. I majored in it in college... which is why I'm a leathersmith...I have a useless degree because I was an idiot in college. Encourage your kids to study a hard science so they don't end up a grumpy old man playing with dead animal skins.
Don't start an email with "This should be easy for you..." If it's easy, you make it or get a Cub Scout to do it. Sure, it will look like a 10 year-old made it, but hey... it was easy.
You won't get arrested for trying to break the laws of physics... because you can't break them. Don't try.
If you design something thinking it is going to be some great and wonderful thing, have me make it out of leather, then realize perhaps your engineering skills were a little lacking, and you didn't take the hints I gave like "that will never freakin' work" or "have you been smoking crack again?" or "Can I speak with someone running the asylum you are at?" Well, that's on you. I try to be a bit more diplomatic about it, but I am a crotchety old cuss, so there you go.
Ladies... unless he is wearing a diaper, you can't change him!
Don't contact me unless you are willing to open the purse strings within a day. The "I'm thinking about getting a whatever made next year..." I don't know if I'll be alive next week. Don't waste those precious minutes I have left. I could be doing something else like yelling at kids to get off my lawn... I live in the desert so it more like "Get off my dirt!" but you get the idea. And after several emails, don't go... I get paid on Thursday so I will pay then. Well, I told several ladies I would gladly marry them on Thursday for a Honeymoon today. Nope. That doesn't fly here... and ladies, don't buy that line either.
Do not just PayPal me money. I don't do refunds. PERIOD! If you mess up and PayPal money, then want a refund because you changed your mind on something... better figure out something else you want that comes to the same amount. This is the fee you pay for being stupid. As John Wayne once said: "Life is hard. It's harder when you are stupid."
Never just ship something to me. I'm not always out on the front porch yelling at kids playing in my dirt. Email me first telling me what you are shipping to me, and what day you are shipping it. Put a note in it telling me what you want. I can't remember what I had for breakfast so I probably won't remember what it is you wanted by the time the package arrives.