Aware of his talent, André knew he had to learn the techniques before starting anything. At the Art school, in the studio of his revered Master Charles Walter, he learnt the techniques of etching and practiced by copying the most famous artists. To meet Waltner's requirements, he had to make 20 different states on his copper plate to achieve a copy of "Night" by Michelangelo. Very rapidly, he made his own personal prints including "Dead Mice" which revealed A. Jacquemin as a great animal engraver.

When he was not at school studying Art, André was visiting Paris with both eagerness and enthusiasm. He actually kept this enthusiasm his entire life. He visited all the museums to learn more about the masterpieces of past and present. One day, Rue de Seine, he remained captivated before a pencil sketch, "le Repas Frugal", signed by Pablo Picasso.
He rapidly made a network of friends and acquaintances. In 1925, he underwent military service at Fort de Domont outside Paris together with Louis-Joseph Soulas and Edouard Mac-Avoy. 4 years later, with a few other up-and-coming artists including Yves Alix, Amédée de la Patellière and Jacques Villon, André Jacquemin founded "la jeune Gravure Contemporaine", a society of Printmakers.

In 1930, he simultaneously received the Fondation Florence Blumenthal prize and an allowance to go on a study trip with his painter friend Pierre Lepage during 14 months to Morocco via Spain. Before his departure, André meets Lyautey, from Lorraine like himself.
Lyautey gave the two young artists letters of recommendation to travel safely. One day, a Maroquies shepherd saw the letter signed by the old Marshal of France and screamed "Kif kif Mohamed, he will never die".
Fes, Meknès, the Anti-Atlas Mountains : Morocco was a major aesthetic shock to André. The beautiful watercolours of this period showed a very subtle sense of colours and observation and revealed that André had mastered the techniques he had once learnt. His apprenticeship was complete