If you're selling at bargain basement prices, then sure, discounts and giveaways, prize draws, tat stalls and balloons.
But, if you're going for a bit further up the food chain, then you need to have impeccable service. Great client communications where you set the expectations, then exceed in delivering and meeting them is crucial.
Stay in touch frequently. Communicate with them and give value - whether it's information, entertainment, pointers, new ideas, expanded horizons, or whatever you can do to WOW them - that's how you stay relevant.
However, keep in mind one simple rule. People buy from people they like. Some will put up with higher prices, slower turnaround time, a mis-speeled word in your website, etc. - if they like you.
I go out of my way to shop at the local butcher because they're fun and the meat is better than anyone else's. I drive 20 minutes out of the way to get Starbucks instead of Costa, because it tastes better. On occasion, I pay way to much for a computer because of the quality and support.
See the pattern? Quality, service, quality.