When you get coins in-game in Temple Run, you can spend them on upgrades like Invisibility (which makes you invulnerable to obstacles), a boost that shoots you ahead like the Bullet Bill in Mario Kart Wii, a Coin Magnet that means you don't have to steer to collect coins, and others. Each progressive level of these upgrades costs more coins than the last.
What's the most sensible order to upgrade them in? Boosts and invisibility help me get further, but coin burst and the mega coin thing help me get more coins with which I can buy more boosts and invisibility sooner.
Is there an optimal order for how I should spend my upgrades? What are the different strategies I could apply?