General question about what and when to study

title is pretty self explanatory. I've been using Lingq, Drops, and a bit of colloquial icelandic (great book). I know about 250-400 words. I know in language learning, that there is no usual set rule or structure on what to learn first, besides the most basic things. but as of now, I really only know the present tense of certain verbs. ill be honest, i find myself not studying verbs enough, which is more of an issue with myself than anything else, but i digress. my main question is; should I study the present tense first, or past tense? which should I study more? and when should I start focusing on noun declensions?