...of contacting me (in no particular order): phone call; e-mail; in person cold call; snail mail; personal introduction from a mutual acquaintance; chance meeting at an industry conference or similar type of gathering.
Your odds of getting a response: phone call 0%; e-mail 10%; in person cold call 0%; snail mail 0%; personal introduction 90%+; industry conference 25%.
I won't take the time to explain why these percentages in this post, but if you're interested post back and I'll do so.
Let's assume the possibility of your finding someone who can make a personal introduction specifically to me is remote. Let's also assume you're unwilling to wait for a chance encounter at a conference. That leaves e-mail as your only viable option.
What gets my attention:
1. A compelling message stated succinctly. What are you selling and why will it make my life better? Don't make me hunt for the answer. If I can't figure this out within the first two sentences, you're done.
2. Respect my intelligence. Don't tell me your product or service is 90% less expensive but 100% more effective than anything else on the market. Tell me something that makes sense.
3. Do your homework. If you have my e-mail address then you know something about me, like what organization I work for. What does my organization do? Would your product provide my organization value? If so, what specifically? If not, why are you wasting your time and mine trying to sell it to me?
If you don't get a response from me and follow up with a phone call, in the unlikely event you get me on the phone don't ask me if I remember your e-mail and especially do NOT get indignant when I say "no". Tell me you sent the e-mail and assume I forgot about it the nanosecond after I read it, which is without a doubt what happened. Sum it up in 30 seconds...give me the elevator speech and no more.
If, on the other hand, you get no response to your initial e-mail there's no harm done in sending a follow-up. And another. And another. It's not like the US Internet Service is charging you electronic postage, and my e-mailbox is already so cluttered you're not doing me any damage. It's up to you how many times you want to do that before you give up. In the meantime all you're costing me is the time it takes to hit the "delete" key.
A side note...while I appreciate your desire to be considerate it's misplaced in a sales situation. It's not about manners and etiquette, it's about getting the appointment and then the sale. This is business...it doesn't matter if we like each other or detest each other, it only matters that we respect each other so we can do effective business together, in a business-like fashion.