Is there a specific kapittel to say asking for help in making a decision?

In general there are certain chapters said when turning to Hashem for all different kinds of help, like Mimamakim kraticha (130), and Esa einai (121). But the best prayer is when it comes straight from the heart. In your case, it’s especially appropriate to add this personal prayer, in your own words, in any language, in the middle of the bracha in Shmoneh Esreh: “Ata chonen l’adam da’at”, when asking for help, wisdom and knowledge to make the best decision (right before the words “chonenu me’eetcha…”. ) With best wishes for the right decision, Rav Ari Shvat