Do your clients Like you?
The second component of the three-letter acronym KLT is Like (the others are Know and Trust). Like is possibly the most difficult of the three to solve for. A client does not have to like you to buy from you, but if they do you will have a much better - and more profitable - relationship.
Think of Microsoft. They have a high dislike factor among their users (when people say “damn computer” they usually mean “damn Microsoft Windows”). Microsoft offsets that by having an extraordinarily high Know factor, along with market structure advantages built up over decades.
Now think of your company. Do clients like you? Or do they tolerate you being around because you do a job they need? If you're in the second category, you may be in trouble. All it takes is someone with a similar product or service, and a much better Like factor, and you may lose a customer.
Don't confuse Like with Trust, either. These can very often be competing factors. I can be best friends with a vendor, love them and their company, but if they screw up the work they do for me, how far will that friendship go? If Like is low and Trust is high, and you break Trust, they will leave. If Like and Trust are both high, and you break Trust, you're in a very dangerous place. Depending on the client, Trust may be all that matters, or their Like factor may be enough to help you recover some of their Trust. But usually, Trust is better than Like.
So how to get to Like? First, and most obvious, is to perform. Deliver the goods and services you promise. Every time you do, the Like factor will change a little (Trust will change much more).
A second way that people improve Like is by going the extra mile - complete projects ahead of time, or under budget. Deliver additional services, without additional cost. Little surprises can help improve your likability (this is dangerous though - include some free stickers in your package to a client and they will get a little delight, but buying dinners or larger gifts can head down the path of corruption).
The third way is by demonstrating your range of knowledge, and adding to it over time. If a potential client compares you and another company, what do they see? More services, more information freely available? That's who they will go with. And over time, if you offer them more and more (both free and paid) they will Like you better.