Generally, I go with wiktionary which is reasonably comprehensive. I remember as an undergrad being stumped by a word in the Septuagint that I could not make any sense of and now I imagine I can search on the inflected form on wiktionary and know exactly where I went wrong. (I would note that as an undergrad I was also pretty thoroughly defeated by Attic Greek. I’ve since learned that the textbook we used, Hansen & Quinn, is pretty rough going, but I’ve also found that the approach taken by the Biblical Greek textbook I worked through (N. Clayton Croy) made what was nearly impossible forty years ago a breeze on the retry nine years ago.