hi, there are verb paradigms on the net, eg : http://socrates.berkeley.edu/~ancgreek/ ... gms_U.html
but i don’t know of any resource where you can put in a grk verb form and it will give you a full paradigm.
this however is an advantage over latin, not a disadvantage: the paucity of grk resources for producing quick answers means that you need to need to really learn how the verb works. this requires more initial work and determination, but once it’s in your head it will stay and will come naturally.
(i admit i’ve been reading the grk orators recently and unconsciously copied demosthenes’ form of argument for the future advantage of a current disadvantage – but in any case i do think this is true, that the lack of easy answers in grk is an advantage for long-term understanding.)
the best tip i can give – one i used when doing my textbook exercises – is to use a 2 step process for writing a verb: first, separate all the parts of a verb with hyphens, then take out each hyphen and see for each removed hyphen whether any phonetic changes need to be made – vowel contractions, consonant assimilations etc. (and note in your book the rule you’ve followed).
what are the parts of a verb? you can use a visual diagram like this to help you (from the best book on grk verbs in my opinion: duhoux’s le verbe grec ancien, pg 34):http://books.google.fr/books?id=IfCKYns ... &q&f=false
what are each of these parts and when do you use them? this comes from learning the grk verb from any textbook.
e.g. to get to ἐφοβεῖτο, you start with the verb’s stem φοβε-. it has an ε at the end because the verb comes from the noun φόβος. then when you put in all the other parts required for ἐφοβεῖτο, you get: ἐ-φοβέ-ε-το, ie. augment, stem, thematic vowel, secondary termination. then when you take out the hyphens, the first one come out without any change, the second hyphen coming out gives εε which contracts to ει (see tables of vowel contractions) and the accent becomes circumflex (see accenting books), and the last hyphen comes out without change.
i recommend working all the way through a short book on verbs like tiarks, which i linked to in this post: viewtopic.php?t=11778
. i did this and found it really helpful.