I like to use separate skewers for meats and vegetables. For meat I keep the pieces very close to each other with a only a small space between for a bit of circulation. For vegetable skewers, I simply make sure the chunks are of equal size. For me, separating the meats from the veggies insures easier control of cooking times. Then the meat and vegetables can be removed from the skewers and combined on a large plate for serving.