Sorry pressed send too soon but generally read a lot of convos and take note of how they transition. Try to make the dialogue have a purpose (depends on what your fic is about. Obviously if you write crack, the purpose is usually a) funny b) establish characterization c) set up future funnies etc. also, ease drop in people in public, see how people talk naturally and then refine out the er and ums. Listen to a podcast, and get to know who you’re writing. Talk to yourself in the shower