The Shield is a good first upgrade due to its low cost, and should be upgraded twice as soon as possible. Also get the two Cape upgrades because longer gliding will give you greater control over your runner. Boosts such as extra lives, Bull, and Hermes should be done later in the game when they are needed. Purchasing the extra life always costs 200 coins, while continues cost 300 coins. It is usually better to purchase continues, since they will not be used until needed, while an extra life may be wasted if it is a bad run.