Any pattern with smaller pieces is more challenging than the exact same pattern made with large pieces. So you could try those same patterns on a smaller scale than you made before. When you are ready, a pattern with half square triangles is more challenging than one with only squares and rectangles, but I'd stick to larger units at first to avoid frustration. Blocks like Churn Dash and Shoo-Fly would be good starters. You can find lots of free block patterns on quilterscache.com. I would just avoid patterns with long skinny triangles or flying geese for now, and just stick to those with half square triangles. Great question, and you are a wise "new-er" quilter to have asked it!