If you are looking to improve your declarer play, one of the better options available is Bridge Masters, a wonderful piece of software that affords you the opportunity to test yourself against hundreds of problems at five different levels.
Every one of the constructed deals illustrates a technical point. Taking the correct line will lead to your making the contract, but if you make a mistake the program will exploit your error and ensure the contract fails. At the end of each deal you can read an explanation that explains the correct line and the thought process behind it. The program was created by BBO founder Fred Gitleman and is available free of charge.
Of course... the very best option to improve your play and your bidding is to attend one of Dominic's classes or seminars! (See https://www.allthingsbridge.co.uk/classes for details.)