Next time, I'll make a list on my palm so the conversation doesn't run dry.
Literal
Next [topic-は] topic [subject-が] not-break-off [in-order-to-ように] palm [on-に] list-up-[preparatory-しとく][volitional-う].
A planning thought. リストアップする ('to list up, to compile a list') is wasei-eigo. ~ようにする ('try to X, arrange so that X') marks a preventive/corrective intent. しとく is the contraction of しておく ('do in preparation'). 手のひら ('palm of the hand'). The absurd detail of writing on one's palm is the comic element — a classic desperate tactic for awkward conversations.