Well keep in mind I’m an industrial contractor so what I do might be different. First thing buy safety glasses (tinted), heavy leather gloves, and a long sleeve shirt or jacket that is somewhat fireproof. Synthetics are a nonstarter. Think cotton hoodie, duck jacket or shirt, denim industrial shirt, etc. Jeans, overalls, or duck pants too. You will thank me later when you try to do it in short sleeve shirt the first time nd get slagged.
Really this is a metal working tool. So I use a cutoff disc for making cuts in sheet metal, unistrut, railings, etc. It’s fast. Not as fast as a cold saw but better than others. I can do decent cuts to cut a display panel into a door but it takes practice. A reciprocating saw and cold saws are neater on the edges but there’s no grinding after. Forget about perfect inside corners. Always cut from the noncosmetic “back” side. If nothing else the slag you throw burns paint and other finishes. Second a word about these. Sometimes there are voids in the cast material or invisible cracks. And it gets weaker as it wears down. So first never take the guard off. Adjust it as needed to protect yourself. Second when you mount any wheel or disc spin it up to full speed pointed away from you and by anyone else to see if it wobbles or flies apart. Third these are consumables. Toss it when it gets worn down close to the hub or gets ragged or chipped. Fourth never try to use it as a grinder or doing curved cuts. Side loading is an absolute no no. If you pay extra for the diamond wheels they last much longer, enough to offset the cost, and the wheel is solid stainless so they are far less prone to dangerous failure. But hey I understand if you buy one wheel for $4 And it lasts you for a year where I buy a 5 pack and sometimes have to bum one or two off someone else on a one day job. Diamknd wheels are slower though.
Then get a grinder wheel to clean up cuts with this, a torch, saw, etc. Use wire wheels or the padded scuff type wheels for paint and dirt removal. Wire wheels also make the brushed finish effect so,me people like. I buy cutoff wheels in packs of 4 or more. Everything else lasts a little while. Only thing with a shorter life is battery charges. I can’t really think of any nonmetal use for one. It just burns wood and plastic trying to sand with it. You could do tile or concrete but that’s what wet saws are for other than maybe wire brushing or aggressive softer brushing.