Parameter searching:
grid search
Bayesian Optimization: SigOpt is providing parameter tuning service based on Bayesian optimization. This is a good place to start.
Spectral Optimization: Harmonica [github] currently only supports tuning binary parameters.
Model ensembling:
- different initialization
 - different epochs
 - different hyperparameters
 
Resources
A toolkit sealing all types of parameter tuning methods: Google Vizier