There are loads of pre season endurance and sprint sessions they can do. One of my favourite ones is use all the lines on a rugby pitch, sprint out to each line and jog or walk back depending on fitness. then work your way back down through each of the lines until back to the start..its a great one to start off with. Speed training u can do 10-20 metre sprints but starting from different positions on the ground ie lying face down, toes pointing in direction of running, face up etc. A good tip I got is to take turns in saying "go" it improves reaction times of players. Hope this helps..once they know what they're doing they are easy ones to do alone or with a team mate.