There is no rule that turns intention into a verb: it does not end -ation, so you cannot drop the ending and add an r. But you know what intention means, so when you hear a verb like intento you can work out what it must be.
The -o ending is what shows this is "I", the same -o that is in quiero.
Intento publicarlo · Intento administrarlo · Intento imitarlo
The h is written in convertible words but never pronounced. Do not even think it, or it will have a habit of slipping out. Imagine the word starts with the vowel instead.
The one exception is ch, which is pronounced like the English /ch/.
A Spanish v can sound like an English /v/, or like a soft b. Generally in the Spanish-speaking world it is the soft b, so make that association between v and soft b now. Around Argentina and Chile you hear far more of the /v/ pronunciation.
To feel the difference: hold a small piece of paper in front of your mouth and say an English word like bucket. The paper moves, because that hard b is a plosive, a burst of gathered air. The Spanish soft b does not have that burst.
In visible, keep the s a real s. English pulls it towards a z, /vi-zi-ble/, and that is not what you want.
Voy is I go or I am going, spelled v-o-y. Hook it to the English word voyage to see the connection with going.
Ahora (a-h-o-r-a) is really the two words a and hora combined, so it is something like "to the hour". That hands you two more words for free.
Voy ahora · No voy ahora · Quiero visitarlo
To reach visitar, the route is not a rule but the word visitation, as in visitation rights. It is a word that exists in English but that we only use in certain contexts, and that is enough to convert from.
A sentence you assume you cannot take on becomes possible if you build it in pieces rather than all at once.
quiero · cancelarlo · pero · no quiero · cancelarlo · ahora
Quiero cancelarlo, pero no quiero cancelarlo ahora.