I start at the center when making a large quilt, just because I know deep inside that this is a hard as it gets. It can only get easier from there. For a smaller quilt I start anywhere. If you have read and watched videos, just get your courage and try. Trial and error is the only real way to learn. No need to be afraid, just prepare a few mock sandwiches and quilt away. Make sure you have the right foot and needle, machine correctly threaded and good thread. Good luck. Make sure you throw away the first few samples if they don't look great.