The Training a Classifier tutorial 165 uses the CIFAR10 dataset, so you might take a look at their model and use it as a baseline.
If you would like to resize your images, you could use:
transform_train = transforms.Compose([
    transforms.Resize(224),
    transforms.RandomHorizontalFlip(),
    transforms.ToTensor(),
    transforms.Normalize((0.4914, 0.4822, 0.4465), (0.2023, 0.1994, 0.2010)),
])

transform_test = transforms.Compose([
    transforms.Resize(224),
    transforms.ToTensor(),
    transforms.Normalize((0.4914, 0.4822, 0.4465), (0.2023, 0.1994, 0.2010)),
])

If you want to use the random cropping, you should resize the images to a larger size (e.g. 240) and crop them to 224.