I may have missed it, but I think you asked for ways to avoid the dangers of third-party wallets? Well how about don't use them and use a Trezor, Ledger Nano instead? I think an easy to use hardware wallet is ALWAYS the way to go. Some people think they are expensive, and I get that, but once you lose your coins (like we all do) because of a scam, or you can't remember your password (how many BTC are frozen because of that) you will see that $100 (or so) is a great deal.

I think those little devices are great.

Here are way to get them:

https://shop.trezor.io/?h=7472657a6f722e696f (buy a Trezor here, direct from the maker, much safer than buying elsewhere, a Trezor One is good enough, you don't need the new fancy version)

https://www.ledgerwallet.com/products/ledger-nano-s (buy a Ledger Nano, direct form the maker)

These things take about 15 minutes to set up and then your private keys never touch the Internet.

I read an article once about a guy who tried to hack his own Trezor. I think he failed, but I learned a lot.

https://www.wired.com/story/i-forgot-my-pin-an-epic-tale-of-losing-dollar30000-in-bitcoin/