Here are some pointers:
(1) Say you want to practice and improve your biblical Hebrew. An excellent point of departure: The Westminster Leningrad Codex. Strip a passage of its verse numbers, vowels and cantillation marks, and sight-read it. Compare your pronunciation with that of an excellent reader, Avraham Shmuelof, available here thanks to Gary Martin of the Academy of Ancient Languages; and here, at the Mechon Mamre site.
(2) Say you can’t figure out a word, how to parse it, or what it means. Perhaps you are puzzling over the beginning of Hosea 4:6:
נדמו עמי מבלי הדעת
The lexicon function of this site is chock full of false and misleading information, but still, if you use it in conjunction with KJV, parsing and a contextually appropriate gloss will usually be at hand if your knowledge of Hebrew grammar is not completely insufficient. There, in the lexicon function, you will discover that נדמו is from damah and that KJV translates “are destroyed.” By clicking on that gloss at the top of the lexicon function, you can recover the corresponding Strong’s number: 1820. Plug that in here, and you will be given, among other things, the relevant entry in an English translation of Gesenius’s Lexicon in the public domain. Better yet, look up דמה in a dead-tree dictionary of your choice on your shelf. Alternatively, you can plug damah in here (set at “Hebrew word”) for a bird’s eye view of the verb’s semantic range. But there are three verbs דמה in ancient Hebrew, and דמה in Hosea 4:6 was understood by some of the ancient versions, for example Aquila and Theodotion, to mean ‘were silent.’ If you are working through Hosea, you must also equip yourself with a very good commentary – to begin with, that of A. A. Macintosh (ICC; 1997).
In short, online resources, at least for now, can only get you so far.