Place modifiers on the thumb keys or - if you don't have any of those - use home row mods!
My ranking of measures from most effective to least effective:
1) Do everything you can to minimize workload of weak fingers (pinky & ring fingers). Just flipping control and caps lock is often not enough.
2) Split keyboard; halves roughly shoulder-width apart. Optimize for straight wrists both at rest and "in action". This usually results in zero tilting or slightly negative tilting.