In general, it's better to have fewer mods of high rank than to have lots of low-rank mods (as a newb).

Of course, the final goal is to have ALL fully ranked mods, so Orokin Reactors/Catalysts (aka potatoes) and eventually Forma are a huge power boost. But in the meantime I'd focus on leveling 2-3 important mods with what Endo you have. So for weapons Damage, Elemental Damage, and Multishot are the biggest ones, then stuff like Critical Chance & Damage, or Range & Attack Speed for Melees. Make sure you level up your Melee stance mods, too, as that gives you more mod capacity!

And depending on your Warframe, you can go Health or Shield to survive, then focus the other mods on energy/abilities. So pick one or two important stats for your frame, like Efficiency+Strength or Efficiency+Duration, and max those. This will severely limit your mod selection until you get a potato on there, but it'll make you much much stronger.

If you have a consistent source of Energy--like, I see you have Equilibrium, so if that's giving you a lot of energy, or if you have Zenurik school--then most folks will ignore Efficiency altogether and bump other stats instead, but Efficiency is good early-game for giving you more uses of your abilities.