Learn Italian: Seguo il consiglio del medico. - I follow the doctor's advice.

No, consiglio is a regular countable noun! While in English we have to say "a piece of advice", in Italian you can simply say un consiglio. If you have two pieces of advice, they are due consigli.

Why do we use del medico instead of just di medico?

To say "the doctor's advice" in Italian, we literally say "the advice of the doctor". Because it refers to a specific doctor, we need the definite article il. When the preposition di (of) combines with il (the), they merge into the single word del.

Is seguo a regular verb?

Yes! It comes from seguire (to follow). It follows the normal rules for -ire verbs: you drop the -ire and add -o for the "io" (I) form, giving us seguo.

What is the difference between medico and dottore?

They are often used interchangeably when talking about health. However, medico specifically means a medical doctor or physician. Dottore is technically a title for anyone who has graduated from a university, though in everyday conversation it is the most common way to call for a doctor.