As far as possible avoid grinding spices. Storing them in leaf form will retain their flavor for a longer time.

Store ground spices in firmly closed dry containers. Stack the containers in cool, dry places. Never store spices in close vicinity to burners, the heat will only make them lose their flavor fast.

Discard herbs/spices that have lost their aroma.

Fast drying herbs/spices retain their flavour for a longer time.

You could dry them in an oven. Place the herb/spice to be dried in a foil-lined baking dish and bake until they are dry and brittle. Remove the leaves from the stem and store in airtight container. Voila, you have a fresh stock for the year.

These can also be dried naturally. Tie the herbs/spices with a string and hang them upside down at a place with plenty of sunlight and air circulation. They should dry in a few weeks' time. Pluck out the dried leaves and store in a jar kept in a cool dry place for about a fortnight till the leaves turn brittle and dry.

You could even microwave herbs and spices! This in fact is the fastest process to preserve them. Spread them (when they are slightly damp) on a paper towel and put in a baking dish. Turn on the microwave for a minute. Remove the dish from the microwave. Mix the condiments and microwave for another half minute. Crush the now brittle spices and sieve out any twiggy remains. Store these in spice jars for future use.

Spices can also be frozen for future use. To do this, wrap them in a foil or plastic wrap and store them in the freezer. Alternately, you could make cubes by adding a bit of water to an ice cube tray and storing spices in these. Drop in a frozen spice when you need to spice up your cooking.