Ravelry is a great place to start, as mentioned since it has a wide selection of patterns for different skill levels. If you want a cozy, structured feel, wool blends work well, while cotton is breathable and better for layering. Circular needles are ideal for cardigans, but make sure to check the recommended size on your yarn label. A gauge swatch is a lifesaver! Nothing worse than putting in hours only to end up with something that doesn't fit. Are you aiming for a fitted or more relaxed style?