According to Psychology for Dummies, various practices including mediation and hypnosis can be used to safely and legally alter your state of consciousness. Alcohol is another legal way for those over 21 to alter consciousness; however moderation is key to ensuring that it is used safely.
According to Psychology Today, certain types of meditation can be used to alter your state of consciousness. This source lists three components of successful meditation: body, breath, and thoughts. The first has to do with assuming a restful position like sitting, followed by conscious control over your breath. The thought aspect of meditation reflects concentration on a particular object of facet of experience which produces an awareness of your thoughts.
The effects of hypnosis on consciousness are debatable, and according to The Scientific American, it is not a distinct state of consciousness as it is often claimed to be. This source cites researchers who find that the results of hypnosis are often caused by expectations about what hypnosis entails, rather than the hypnosis itself. However, according to Psychology Today, hypnosis often shifts awareness towards the characteristics found in sleep and dreaming without actually falling asleep. For this reason, this source claims that hypnosis can be considered a form of altered consciousness.
Alcohol use can alter your consciousness significantly by reducing negative sensations and producing feelings of euphoria. However, alcohol use in large quantities can also result in impaired judgement and adverse physiological effects from alcohol toxicity. The U.S. National Library of Medicine recommends drinking alcohol in moderation, which they define as no more than 1 drink per day for an adult woman, and 2 drinks for an adult male. A drink is defined as 12 ounces of beer, 5 ounces of wine, or 1½ ounces of liquor.