Ingredients
Solid Ingredients, listed in order of personal preference:
Cloves
      These are super-christmasesque. Too many cloves in your tea can make your tongue go numb, which is sort of annoying, because otherwise they make a great breath freshener when chewed!
Black Tea (preferably Earl Grey)
      All the tea i use is very stale, and thus I end up using much more of it than is likely advisable. If you have fresh tea, you may want to use less than my suggested amounts.
Cardamom seeds
      These are pretty very strong, and will overpower your tea easily. They numb your tongue, too! But, you need them, because they add some spicey kick to your chai.
Peppercorn
      These are spicy and are good for when you want really peppy happy tea! One per cup should do it.
Cinnamon (sugar, sticks, powder, et al)
      Cinnamon powder is very strong and should be added carefully, cinnamon sugar is not preferable because I personally dislike sugar in chai tea. Cinnamon sticks are great if you can find them.
Pumpkin Pie Spice
      This is just a mixture of a bunch of various pumpkin-y ingredients, many of which are already in your tea. Don't add too much or else you won't be able to taste anything else in your brew!
Dried and ground hot peppers!
      Obviously you need just a few infinitesimal specks of this in tea, if any at all. Nonetheless, it can make your tea very spicy and peppy happy if used!
Nutmeg
      This is christmas.
Ginger
      Add to taste. Don't grind whole ginger stem, peel it and then cut it into thin strips, then slices, then throw it in the pot.

Liquid bases, in order of preference:
Soy Milk
      Vanilla Silk is the best! You can boil this and it won't scald or nothin'. Tastes great with honey.
2 part water, 1 part warmed milk
      Be sure not to warm milk too much, or else it will scald and taste rotten! Never boil milk.
Water
      Meh. This is for breakfast tea.

Sweeteners, in order of preference:
Honey
      Delicious! Add bit by bit, as too much can really smother the other flavours.
Vanilla
      Add slowly. Not a substitute for actual sweeteners.
Brown sugar
      This sort of tastes like a cross between honey and sugar, and if definitely preferred over the latter.
Sugar
      Yuck! This is for coffee. Really bad coffee.

Personal Notes

All ingredients must be added carefully, as too much of any single ingredient often sticks out like a sore thumb.

You could grind ingredients with a mortar & pestle, however I usually pulverise them into a fine powder with a coffee grinder. This way, you end up having to use less, as their flavour will be more efficiently absorbed by the water/soy milk. But, then again, you may prefer the traditional way of grinding ingredients.

You can put all of the ingredients in a tea bag and steep it in a teapot after heating up your water/soy milk, but you often end up with a papery flavour. To avoid this, I usually brew the ingredients with the water/soy milk in a pot or pan on a stovetop, and then filter them out when pouring.

Amounts

Sorry, I don't measure anything when making tea, so I'm just going to guess. I suggest that you learn to add ingredients by taste, it's much more fun and you get to know your ingredients a whole lot better.

1 standard mug size's worth of soy milk or watermilk whatever you're using.
Roughly 1/3 of a teaspoon, of the following spice mix:
      5:1 clove/cardamom ratio
      4:1 cardamom/peppercorn
1 tablespoon tea leaves
Dash of nutmeg
Dash of cinnamon powder and/or pumpkin pie spice
A few grains of dried and ground hot pepper
1 tablespoon of honey

Steep until you have something that suits your taste buds.