Many of the irregular verbs are among the oldest and most common words in the English language and they play a vital role in forming past and perfect tenses, passives, conditionals and reported speech. That's why learning to use them properly is the simplest and best way to quickly improve your performance across the board in English
The VerbBusters website offers what is arguably the most complete set of resources on this topic on the Internet. The home page features a fun quiz type activity where learners from all over the world compete on six levels to rack up the best score in the shortest time. The quiz can be used in English-English or Native Language-English modes and currently supports, among others, Spanish, German, French, Italian, Portuguese and Chinese.
Bilingual verb lists in each of these languages are provided for each level and a search engine allows you to check the forms and hear the pronunciation of all the verbs in the database. Visitors to the site contribute to building the database by adding entries for their language to the Wiki, which also includes a complete morphological classification of the irregular verbs.
And if you want to brush up your skills on the go, you can try the free demo app available for Android.