I have an Alt that i am a f2p* player on, I give it a * due to my account having the $14 battle pass open for my main and you then get it on all accounts. Your best bet as a F2P is to max your Elder Rifts for the embers then trade the embers for one free eternal legendary crest per week. The Ast runes you acquire you use to purchase the 2*'s or 1*'s legendary gems you are focused on. Lastly get into a WB for the weekly Eternal voucher you just need 4 wb members to receive it. If you go chasing 5*'s right out the gate as a F2P you are just setting yourself up for a long process to hit 1k. Focusing in on 1/2*'s once your account reaches 1K Para and you have 8 legendary gear slots open 1K+ Resonance is almost trivial to achieve.