How to create user profile theme hook suggestion for custom template?
It's hard to tell without seeing your code but off the top of my head your preprocess function should look something like this:

function MYTHEME_preprocess_user_profile(&amp;$vars) {
  if ($vars['view_mode'] == 'mini_teaser') {
    $vars['theme_hook_suggestions'][] = 'user_profile__mini_teaser';
  }
}


Or a more generic solution:

function MYTHEME_preprocess_user_profile(&amp;$vars) {
  $vars['theme_hook_suggestions'][] = 'user_profile__' . $vars['view_mode'];
}