Tomo una ducha por la mañana.

Both are correct ways to say “I shower,” but they use different verbs.

• Tomo una ducha literally means “I take a shower,” using tomar
  • noun.
• Me ducho uses the pronominal verb ducharse (“to shower oneself”).
  Choice is stylistic; tomo una ducha can sound slightly more formal or neutral, while me ducho is straightforwardly reflexive.

In Spanish, singular countable nouns generally require an indefinite article when introduced for the first time.

• Tomo una ducha = “I take a shower.”
  Omitting una (e.g. Tomo ducha) sounds non-native or poetic. Always say una ducha for “a shower.”

Por la mañana means “in the morning,” used for habitual or unspecific times of day.

• En la mañana can appear in some regions but is less common for routines.
• A la mañana is not standard in this context.
  Always use por la mañana to express “(as a routine) in the morning.”

Spanish uses the present indicative to describe habitual actions, just like English:

• Tomo una ducha por la mañana. (“I take a shower in the morning.”)
  No need for adverbs like siempre or regularmente to indicate routine, unless you want extra emphasis.

Yes, you can say:

• Por la mañana tomo una ducha.
  This front-placement emphasizes the time (the morning) but doesn’t change the overall meaning or tense. Spanish word order is flexible.

You would only say tomo la ducha if you refer to a very specific shower already mentioned or known:

• “¿Cómo estuvo la ducha?”
• “Tomo la ducha de la habitación de hotel.”
  But for general routines, use una ducha.

Simply invert the subject and verb, and add a question mark:

• ¿Tomas una ducha por la mañana?
  If speaking formally or to more than one person:
• ¿Toma una ducha por la mañana usted? or
• ¿Toman una ducha por la mañana ustedes?