I agree with Megan and Glaxony.
Herbs can generally be taken in any form.
The most widely used intake of herbs (worldwide) is in form of tea.
If you need quick action or have an acute condition, tincture is best used - the alcohol delivery goes into the bloodstream. While taking tincture in warm water, it is a bit more effective to lift the tongue so that the liquid can be delivered via the glands under the tongue.
Powered herbs in pill form are good too. However, there are some problems if the herbs were cut at a high volume causing heat to penetrate the herbs. This would release some of the volatile oils; thus, degrading the effectiveness. The other problem is that a product could be on the shelf too long or the herb quality was inferior to begin with before putting them into pills. It's best to make your own pills and grind the herbs yourself. Unless, you're familiar with a company who is known for high quality products, it's hard to tell what you're getting.
I hope that helps.