Practical and practicable are both adjectives with related meanings, so from a structural viewpoint, they often could be used interchangeably. But the differences in their definitions make one word more appropriate for a given context than the other.
Practical is used to describe something concerned with practice rather than theory or something that is likely to be effective in real circumstances or someone who is realistic in approach. On the other hand, practicable means able to be done or put into practice successfully. These meanings are very much related but also significantly different. The more effective writer will consider those differences when selecting between practical and practicable.
For example, we could say
Be practical with practicable. Precision of language can provide that extra level of professionalism which will reflect back on you and your brand in the minds of your audience. So give proper attention to precision in your language when you write. That in turn will yield a more effective presentation of you and your brand.