If you like listening more than talking then you're halfway there.

Showing warmth and that you're not a dick means listening to other people and responding to what they say (In my opinion). That may be an oversimplification.

I went for lunch with my sister a few months ago, she was having trouble making friends and being warm and open to new people. When the waitress came over I chatted with her a little bit and joked around because she nearly tripped as she approached our table. When the waitress left my sister asked me if I knew her - I didn't. She thought I had because of how we were talking to each other. I gave her a tip that she said completely changed how she approaches new people - she was already trying to just listen to what other people say and asking questions when it was her turn to talk but the thing that made it click for her was that I suggested to her that she should try pretending that they're already her friend. That tip made talking to new people easier for her. If you talk to people like they're already your friend then it's easier to be yourself, genuine, and warm and be interested in who they are.

It might work for you - your milage may vary.

My personal rule zero is to smile a lot. No matter who it is that you're speaking to, a smile make you instantly more likeable and trustworthy. It's tough to get used to (especially if you're the kind of person, like me, who frowns as their natural expression). I think of it like this though: no matter who it is that I'm speaking to, they're taking time out of their lives to listen. A smile shows appreciation of that. (Not to mention that smiling a lot helps you live longer [1].)

[1] http://www.ted.com/talks/ron_gutman_the_hidden_power_of_smil...

Ask yourself: do you tend to like the bigmouths better than someone who's genuinely trying to have a conversation with you? Does lots of talking really help to establish warmth? It doesn't. The best sales people are awesome listeners - and ask the right questions. If you feel uncomfortable to do the talking, ask your prospective customers about the problems they're facing (related to your solution). Unsurprisingly, most people are quite happy to talk about their problems. Note that this is how most friendships start, too.

>How DO I "establish warmth" if I'm naturally inwards-looking person that likes listening more than talking?

The best salespeople always listen much more than they talk, so you are fine there. Of course, you actually have to listen, rather than tune out. If you really listen well, that is a major advantage in sales.

>The best salespeople always listen much more than they talk //

Hmm, I don't know. I think such salespeople may be the ones favoured by the crowd here. Though not exclusively, others have mentioned those that attempt to educate you as being better (IMO that means they're talking more, answering your questions).

I'm not prepared to accept thought that being more likeable translates to better sales figures in general without some hard evidence.

Do companies turn down the best financial offer because the salesperson is a pillock? Can't see it happening much unfortunately.

Have a firm handshake, smile and try and see things from the other person's point of view.

Remember people's names, remember the names of their children and their spouses. Ask how they are doing, in general most people care far more about that then whatever their company does.

Smile more often (you don't have to be grinning ear to ear, just any facial expression that has a modicum of happiness).

Touch base with people whenever possible.

If you're a naturally inwards looking person that likes listening more than talking you've got half your problems solved, all you need to do is start asking questions and be sincerely interested in what they have to say. The only thing people love more than talking about themselves is having someone to listen to it.