Grietjekarwietje: Het netjes afwerken van je haakwerk - This is a cool way to do an invisible join. The page is in Dutch, but can be translated by clicking an icon to the right. There are also photos which clearly show the technique.
Crochet loose ends. Crochet over tail ends as worked of first stitches, pick up ends with a needle & weave back on themselves to outside edge. Snip off at this point. Use method for all stripy crochet (including ripples).