Two suggestions, one practical, the other probably less so.

1) Hold the cup directly, instead of the plate the cup is on. I don't know if that's allowed by health code or restaurant policy, but if it is, you get much more stability from cupping the cup in your hand than balancing it on a small plate. If you're already doing that: practice will get you there.

2) A good cappuccino should be fairly stable. I know there's disagreement about the proper way of layering cappuccinos, but the best ones integrate very finely textured foam into the milk, instead of just layering coffee - milk - foam on top of each other. Milk foamed this way is more stable than regular milk; I've carried cups filled to the brim up the stairs without any spilling. But: this is a barista-side issue, and to be honest, I wouldn't touch it ... the barista is going to make the cappuccino how s/he feels it's best, and being told to do something differently won't go over well.

Train yourself, again and again.

You need to train yourself into pouring the appropriate quantity of coffee and milk in the cup to allow enough foam to create a nice "cap".

(YMMV) The coffee/milk should be about 1/3 of the cup capacity, and the rest if filled with the milk foam.

After that, train yourself in bringing the cup to the customers, try with cups filled with water (less of a mess).

I find that moving/walking slowly tends to spill more than if you move faster; for me I shake less.

Good luck.

Cappuccinos are complex. They aren't overly difficult to make if you are a trained barista - it's just that there is a lot of variation on how to make them.

The two main ways to make a cappuccino:

1. Layering 1/3 espresso, 1/3 foam (wet or dry), and 1/3 milk. Foam is spooned onto the espresso and milk is poured through the foam until full. This should create a nice foam cap⁽¹⁾ on the top, a dark ring of espresso around the rim, and a small spot of espresso in the middle. Observe (Note, however, this picture doesn't have the dot of espresso in the middle):
2. The better way (in my opinion)! After one steams milks and it is allowed to settle (10-30 seconds), it separates into three main layers (especially noticeable in milk steamed/foamed⁽²⁾ for cappuccinos. The layers are:
   1. Bottom layer. This milk is watery and has a bluish tinge to it. This milk is not rich and does not lend to a good cappuccino.
   2. Middle layer. This milk is very creamy and rich. At my cafe, we refer to this as the gold.
   3. Top layer. This is foam. Depending on how the barista stretched⁽³⁾ the milk, this foam is going to be either wet or dry.
      • **To illustrate this layering effect, I have prepared a diagram:*

With method #2, one lets the steamed milk settle into it's layers. (Note that when making milk with this method, more milk must be used and a wetter foam is required) Then, one holds back the foam and milk with a spoon at the spout and very slowly pours off at least half of the bottom layer of watery, blue-tinged milk. The next step is to stir what is left in the pitcher and pour it (continue swirling up until pour for best mix) into the espresso. You get something looking a bit more like this (ignore the art):

This method results in more of a uniform brown color as all the foam is mixing with the espresso.

Differences between the two:

• Method 2 usually does not have a cap over the rim.
• Method 2 does not include the watery milk.
• Method 2 has more uniform espresso distribution.
• Method 1 is usually more aesthetically pleasing.
• Method 1 usually offers more of a straight milk taste before getting to the bulk of the espresso-milk mixture.

How to solve your problem:

So I have given you a lot of information on cappuccinos - which you probably didn't need. The reason I did this is because if your cappuccinos are spilling that easily, the fault lies with your barista.

Your barista is most likely making cappuccinos using Method 1. He/She should adjust the size of the cap over the rim depending on the size of the cappuccino and the foam preference.

If a cappuccino is made with dry foam, you can make a higher cap. It is less likely to spill and the foam will start to dissipate after about a minute, bringing the the cap down (ergo, by the time you get it to the customer, they will still have an aesthetically pleasing cap on the drink).

If a cappuccino is made with wet foam, the cap should not be so high. It is more likely to spill. It doesn't need to be very high anyway as it will not dissipate very much between the barista and the customer.

If your barista is making cappuccinos using method 2 and is pouring enough in to make a cap, your barista should stop this. It isn't aesthetically pleasing and will spill.

As far a tool to prevent spillage, take a spoon and remove some of the foam on top. This is the only way to bring down the level so that it won't spill.

Other than that, evaluate your carrying technique. You may ask some other servers for tricks that they use.

Footnotes:

(1): The cap is what is used to refer to the foam that forms a dome shape above the rim of the mug.

(2): Steaming/Frothing/Foaming milk usually all refer to the same process.

(3): Stretching refers to how much volume is added to the milk during the steaming process by allowing more/less air to be incorporated into the milk.