Suggestion can be divided into self-suggestion and the norms of social suggestion. Self-suggestion is more important for your practice. It doesn’t involve chanting ‘I’m the best’, but rather giving yourself directions when you are in a relaxed mental state. Suggestion affects the subconscious mind, suggesting that our personality should choose between the available options (such as I have faith/I don’t have faith).
A suitable phrase for suggestion will fulfil three criteria: it must be believable, positive and short. ‘I have faith in myself’ is one example of a good suggestion. It’s a good idea to avoid command-like suggestions containing words such as ‘should’ and ‘must’, as they cause subconscious resistance.