I am a F2P player also, for over a year. I’m at level 805.
My strategy with gems was to unlock Jungle Run with Devastator. I bought Omega Supreme next for 750 gems so I had someone from Gestalt squad. I bought Superion next for 750 a little later on. Omega is better than Devastator, but Superion is better than Omega. I use EMP rounds accessory for all of them.
I almost never use gems for event top ups, UNLESS it’s to unlock or overpower a TF that is highly rated and/or needed by me. (I wouldn’t spend gems just to complete a squad if the missing TF sucks.)
With the weekly offers, if a good character is there for 750-1,000 gems, I’d go for it. For 2,000 gems I almost never do. I don’t think I have yet.
<p style=”text-align: left;”>Lastly, I have 2 slots each for Easy and Medium Missions, but recently went for the 3rd on Hard Missions to get all Rewards. (And I unlocked all 3 Spark Run spots early on before anything else!)</p>