Well, before I started my apprenticeship I used to work at a supply house so I have seen both sides of things A few things I like or dislike are

You MUST have counter staff that have some knowledge on the products and how they are installed. EG I have gone into the suppliers looking for a mercury vapour lamp but was repeadedly told " metal halide is the same thing because it says this lamp contains mercury". I walked away.
Flip side, a good counter person will try to make sure you have everything you need. Doing a new service perhaps? If I saw you did not order "part X" I would ask and make sure you had "part X". Many times I was thanked with " Oh ya I need that thanks for reminding me...

Don't make me wait.. There is nothing I hate more than waiting in line, ESPECIALLY when I see one or 2 counter people puttering around and stocking stuff while the line is like 6 deep OR trying to help " joe off the street" wire up a pigtail.
Flip side , when I was behind the counter, we did our best to help everyone, and would help out any CONTRACTOR with whatever they wanted to know but when " joe off the street" came in looking for info, I would tell him to call an electrician. Also, one of the reasons I quit is because they had me working the counter, doing orders, answering the phone etc while the boss son
( other staff) disappeared each afternoon to run personal errands instead of stocking shelves or taking orders, and got away with it every time!


Keep lots of stock especially of the "common" items. Nothing I hate more than is to go to the supplier for something like a box of standard white duplex receptacles and find out they are out of stock, OR go in and ask for something "not so common" like a dryer or stove cord and find out they can order it and have it in a week.
Flip side, I HATED telling customers that "Oh we are out of part X". Doesn't look good on the supply house, and eventually word gets around NOT to go to your supply house because you do not have any stock.

We also had free delivery, but within reason. orders for " good" contractors, (Good as in large orders regularily, and payment on time) We would have it there when they wanted, wherever they wanted. Regardless of how big or small the order was.. For others it would be delivered " morning or afternoon" and would have to be a reasonable order.
( one 1/2" pvc LB delivered across the city was not reasonable) [Linked Image]


A.D