One of the simplest ways to use crystals with the chakra system is to match the color of the crystal with the color of the chakra; crystal healers often call this layout a rainbow array.
To balance your chakras at this level you will need at least eight colored crystals, one for each of the major chakras and a grounding stone, tumbled stones are fine. There will be more about grounding in an article soon!
The grounding stone should be a dark color- most brown and black stones have grounding properties. Hematite or black tourmaline, otherwise called schorl, are a couple of my favourites.
For the base chakra you will need a red stone- try red jasper or garnet.
At the sacral chakra use an orange stone- carnelian is the most easily available
For your solar plexus chakra use a yellow stone such as a honey calcite or imperial topaz
At your heart you have a choice whether to go for green or pink. Most peoples heart chakras vibrate to the colour green when healthy. For those who have become unconditionally loving the heart chakra changes to a beautiful rose pink (dont worry, not many of us have got to this point yet!). Green stones here are calming, try aventurine. Pink stones at the heart feel comforting and nurturing. Rose quartz or mangano calcite are my favourites.
For your throat chakra choose a blue stone. Blue lace agate is very soothing here.
At your third eye, or brow chakra you can place an indigo stone. Try sodalite or lapis lazuli.
At your crown go for a clear or violet stone. Try clear quartz or amethyst.
Ive suggested some of the most easily attainable stones, you may have others that you feel drawn to use- thats fine. You may also get a sense that you want to use a different color on a particular chakra- go with that, as it is your intuition letting you know what you personally need.
Once you have collected your basic set of stones you need to find a time when you will not be disturbed. You may like to play some soothing background music to mask any noise from outside.
Lay down with the stones next to you. Place the grounding stone first- put that beneath your feet, then place the rest one by one on each chakra working up the body.
Once all the stones are on you may like to place a hand over each stone in turn from the base chakra upwards, holding the intention that you are balancing your chakras. You will probably need no more than five minutes to focus on each chakra- let your intuition tell you when it is time to move up to the next one.
When you have completed your chakra balance remove the stones and sit up slowly. Pick up the grounding stone if you feel at all light-headed and hold it for a few minutes. Drink a glass of water and then gently go about your day.
If you'd like to know more about the properties of the crystals you've chosen I can recommend 'The Crystal Bible' by Judy Hall. The text is very readable and down to earth and the crystals are clearly photographed making identification easier.