This handy little book contains a list of the inflected forms of common verbs in alphabetical (Greek) order.
It does not purport to explain or teach you anything, but if you happen across an inflected verb in a sentence and you cannot find it in your dictionary, try this book. The listed form might be aorist or imperfect, perfect or pluperfect. Find the verb that is afflicting you with woe and the central column in this book will tell you the tense, mood, form and number. The right hand column then gives you the dictionary form (first person singular present indicative active / deponent) which you can then look up in your conventional dictionary or lexicon.
I should stress that those students of Greek with some knowledge, say intermediate, will gain more benefit than complete beginners. Sometimes the form given in this book is not the identical one you are seeking (number might be different). But a little common sense will allow you to recognise the root, and then you can find the dictionary form as mentioned above.
I have found this book has become more and more useful as my foray into the world of Classical Greek becomes more ambitious.