better way of caching webservice responces

[xtekno]

My application heavily uses webservices and doesnt use database atall. there is a webservice layer which gets data from database and sends it to php UI. so the phpUI doesnt directly interact with the databases. I want to improve the performance of this application what is a better approach to improve the performance?should I use memcached and cache control headers or is there any other way to implement the caching to improve the performance? I want a way to reduce my Http requests to webservices