Sales has evolved quickly over the past few years--speed has become more important, customer interactions have gotten shorter, and salespeople rarely spend time face-to-face with their customers. Yet in the face of these changes, the core aspect of selling has remained the same: building relationships.

Relationships are defined by the quality of each individual interaction. Interactions in inside sales typically start out as either a phone call with about a 20-second window for reps to engage potential buyers or a short email introduction. With less time to make an impression and a connection, etiquette really matters. 

Here are the rules that I consider most important to keep in mind when it comes time for inside sales to reach out to prospective customers.

Email Rules

1. Leave customers spellbound--not spelled wrong.

Anyone who's ever picked up a Starbucks cup with a mutilated name on it knows how off-putting those errors can be. It's probably not worth getting worked up over a latte, but in sales those kinds of mistakes can be fatal. I'm amazed how consistently I encounter stories about salespeople misspelling buyers' names, companies or other basic information. It might seem unimportant, but especially early in the process that type of negligence can jeopardize an entire opportunity.

In fact, salespeople should pay close attention to spelling and the grammatical accuracy of everything they write. Coming off as sloppy or unintelligent is a good way to alienate prospects before you have a chance to engage with them, and bad grammar is especially damning. (The BBC reported several years ago that spelling mistakes alone were costing British companies millions of pounds annually.)

2. Make it personal.

Personalized emails improve conversion rates by 10 percent, according to Aberdeen Group. That shouldn't be surprising, because everyone likes to feel specially attended to. And yet many salespeople skip this step. They rely exclusively on templates and fail to create messages that resonate with individual customers. Call out each customer's specific pain points to increase likelihood of a leaving a positive impression and winning a response.

3. But don't be a cliché.

Personalization doesn't simply mean throwing the prospect's name into the subject line. One of my biggest pet peeves is getting an email that includes my name in the subject line, because it's an immediate red flag that the email is from a marketer. Normal communications from friends and family don't make a show of naming the intended recipient. The closer sales pitches can be to the types of communications you would get from a co-worker or a trusted college, the better. Natural, conversational language goes a long way when it comes to relationship building.

Phone Rules

4. Persist but don't annoy.

Most sales reps have no problem making a first call attempt to a prospective buyer. Unfortunately they quickly lose interest if they don't get the buyer on the phone right away. In fact 50% of leads are never called a second time according to research on the optimal B2B sales strategy. This gives the sales rep that does persist beyond the first call -- when their competitors have moved on -- a huge advantage.  But be careful not to overcall as it can hurt your brand and reputation. So what is the right number of call attempts? Six is right where you want to be, with 95% of all converted leads are reached by the sixth call attempt, according to the same study .

5. Don't hide behind email.

A lot of sellers today leverage email and social media as their primary means of communication with a prospective buyer. Their hope is that the prospect will take the bait and respond to set up a call. Unfortunately this approach is a huge gambling game, and the odds are NOT in the sellers favor. By picking up the phone the sales rep not only demonstrates that they are a real person, instead of a spam bot, but they also dramatically increase their chance of connecting with a prospect.

Social Media Rules

6. Select your channel wisely.

Social selling is an extremely effective sales approach, with devotees including some of the leading minds in the industry, but it can also be a slippery slope to navigate. All social media is not created equal. It makes sense to add potential customers on LinkedIn and follow them on Twitter, as these are largely considered professional networks and relatively public. Facebook is another story. Most people like to restrict their Facebook network to family and personal friends, not professional acquaintances.

7. Link in, don't creep out.

LinkedIn is a powerful tool. Used correctly it can be a salesperson's best friend, but timing is important. LinkedIn is supposed to be a digitized version one's personal professional network...which means prospects probably won't take kindly to an invite from someone that they haven't met or memorably engaged with. Too many sales reps treat LinkedIn as a way to get a foot in the door instead of a way to fortify an existing relationship. Wait to extend the invitation until after at least one or two meaningful interactions with any prospect. The same rule applies when leveraging text messaging - don't send a text until you've established a relationship with a prospect.

Navigating sales can be a tricky business of balancing both company and customer needs, but the best thing salespeople can do is establish a respectful relationship with their buyers. Following these rules is a great way to start.