Just play normally, there's not much point hunting him until you've got the gear to insta-gib him.
As for soloing: You pretty much need squadmates for Defense and Mobile Defense missions, barring a handful of builds that require you to have a fully outfitted set of specialized gear that you need planetary progression (or loads of plat) to get in the first place. Your best bet is to get a Loki, mod for power duration, efficiency, and reserves, get Energy Siphon, and stealth your way through everything.
Loki's top-tier for a reason: enemies don't target you when you're invisible, and Radial Disarm hard-counters a lot of nasty stuff. Better still, a Loki's the ideal way to spend your starter plat + a little extra: 75p gets you a Loki from the marketplace with a potato already installed (meaning that the actual cost of the frame is 55p) -- it's the only thing apart from potatoes that's worth buying on the market.
I specifically avoid recommending Rhino
because he's so easy to play. A lot of bad players turn him into a crutch, never learn to play without facetanking, and then can't pull their weight in the endgame when he falls off. Learning to play with a super-squishy frame vastly improves your skills because you'll either learn or keep dying over and over.
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On another note, look into
this. He hasn't updated it for the latest changes yet, but it's still mostly accurate (and the Synoid Gammacor continues to be beast anyways) and gives you a very good idea of what to aim for. Some of the God-tier and Tier 5 list items are discontinued, Primes, Syndie gear, &c. that you're not going to get without spending plat or getting to mid-late game, but some like the Marelok, Galatine and Vectis are available and easy to make pretty much right off the bat, even if you don't have a clan, don't play Void missions, don't play Invasions, &c.