Consistency is key!
This is the number one lesson I try to teach new coffee van owners. The best businesses are also the most consistent businesses.
What do I mean by consistent?
I mean consistently reliable, and consistently good.
Consistently reliable
You could be the best barista in the country. You might have all the latte art skills in the book. But if you're not there, available to your customers, at the times and days you say you'll be there, then you'll struggle to reach your full potential.
A 7/10 barista who turns up day in day out, is never late, and always has the same products available, is going to be more successful, in the long run, than a 9.5/10 barista who sometimes sleeps in, or sometimes forgets the soy milk, or sometimes says no to the regulars in favour of a one-off, bigger, better job.
It's all about trust. Your customers have to trust that you'll be there. You can't let them wonder if you will or won't be. You have to instil trust in them so that they will just know that you'll be their source of coffee for the day. If you let them down, even once, you begin to lose their trust, and that takes a long time to build back up!
How can you be consistently reliable? Set your hours, your days, your product list, and stick to it. For coffee vans that have a coffee run, this is almost impossible, but you just need to do your best. Some days one of your stops has 5 customers, other days it has 25. This slows you down, despite increasing your sales, and then makes you late for every other stop during the rest of your day. For many of your regulars, they will be flexible for you, and its OK. But for some, it's not good enough. Humans are creatures of habit. They drive the same way to work every day. They have their toilet breaks at the same time every day. They get their coffee at the same time every day. And if their coffee van isn't there when they expect it, they don't like that! They lose patience, and eventually, they get their coffee from someone else who is reliable.
Lets say you run your business from a drive thru set up, like most of the Van Wild Coffee vans do. You've eliminated your main consistency problem by always being in the same place at the same time (and if you want proof that your customers are creatures of habit, come and stand with us in the morning and watch the same customers come at the same time, day after day). If you normally finish at 9.30am, stick to that time! Just because you get a couple of extras after 9.30 one day, you should think before you serve them. Sure, a sale is important, but if those same customers come back the next day after 9.30, and you aren't there even though you were the day before, they won't be happy! Better to apologise, and say "We always close at 9.30am, hopefully see you before then tomorrow!", then you're not breaking your consistency rule, and more often than not they'll be there before 9.30 tomorrow!
There's no point being there 9/10 days in a fortnight. Be there, on time, 10/10 days. A good rule of thumb is that every day you miss takes a week to bounce back from.
Consistently good
Focus on your quality! If you aren't good, they'll find better. And unfortunately, it only takes one bad coffee to lose a customer.
So, stick to your process. Don't drop the ball when you're busy, and don't cut corners. It's far, far better to make a customer wait an extra 15 seconds for a good coffee, than rush them through and give them a lousy coffee. If the coffee is good, they'll forgive the wait time. If they coffee is average, regardless of the speed, they won't forgive you.
On the same note, look at who is working for you. Customers hate change, and even if you replace yourself with an amazing barista for a day or two, they won't like it. Half of the reason they come to you is for you! And equally importantly, you know that Timmy likes his cap just a little bit hotter, and Sarah likes her long black with a decent splash of cold water. You do it just right. So that means, as much as possible, you need to be the one to do it!
Use a thermometer. So what if the trendy baristas in Paddington don't use them. It's about consistency! Especially when you have multiple baristas. How can you sure they all know what "not too hot" means? The only way is by using a thermometer. It just makes you consistent. The same goes for your spoonfulls of chocolate powder and sugar. What really is a "quarter tea spoon"? Make sure you and all your baristas know exactly what that looks like. Use syrup pumps, and liquid sugar with a simple pump action that always gives you the same dose. It's all about consistency. And it works!
You've worked hard to earn their trust. Now keep it!