Reveal the word
Inhale and exhale three times. Breathe out relaxed. Stick out the tongue and lick your lips doing circles both to the right and left. Touch your upper and lower incisors with your tongue, both from the inside and the outside. Touch the wrinkled area behind the upper incisors.
Put a paper tissue in front of your mouth and utter the words tea and toe. Observe how the paper moves when you pronounce the initial consonant <t>. Try to pronounce the same word keeping the tissue still.
Try uttering the word tassa and then tara in front of the tissue (keeping it still). You should try to pronounce all the Catalan words with <t> keeping the tissue still.
Utter the word estibar. Look that the paper doesn't move while pronuncing <t>. Say it again making a short pause after the first syllable: es-tiba, trying to keep the paper still while pronouncing <t>. Now, say it again separating even more the first syllable: es tiba. Do the same thing with the word Esteve.