When selecting a good squash, regardless of the type, look for one that is heavy for it's size, has a rich color and is free of bruises and blemishes. Summer squash, like zucchini, crookneck, and pattypan should have a bright color. These are best when they are still small. Winter squash, like spaghetti, turban, butternut and hubbard should have a deep color and a hard skin.
The easiest way to prepare squash on the grill is to cut it in half down the middle. Make sure that the pieces are even and are not too thick or they will cook too slowly. Larger squash, and winter squash may need to be cut into three or four pieces. Clean out all the seeds and strings and wash. Next mix together some olive oil with fresh herbs, like basil, cilantro, and oregano. Fresh herbs should be chopped finely. Brush the mixture over the exposed "meat" and place directly on a medium hot grill. You want to get good grill marks on the squash but watch for burning. The concave shape of the squash will trap in steam and help cook the squash evenly. Remove from the grill and serve hot.
You can, of course also cut squash into smaller pieces and wrap in foil alone or mixed up with other vegetables. Grill these packages on an upper rack or off to the side of the fire. Turn occasionally to even out the cooking and prevent burning. Squash can also be placed on kebabs and grilled that way. Look for similar ingredients that will take the same time to cook so you don't end up with some things being overcooked and others undercooked.
Squash is a great source of many essential nutrients and properly prepared are not to be avoided. The quick cooking of the grill and added smoky flavor will make them a treat that the family won't push off to the side of the plate. They also look great on the grill so you can really impress the neighbors with your grilling ability with out even trying.