The two big hazards are you either get distracted or you overwork.

Have a nice spot just to work - don't do it on the dinner table or the sofa. Ideally a chair and table. Don't get too comfortable.

Take lunch breaks. Snack breaks. Bathroom breaks. Make sure to walk around at least once an hour.

Make sure your family members understand you're at work now. Not everyone does.

Sitting too long in a cramped room builds up carbon dioxide, making it harder to focus. Leave a door or window wide open. Don't work in a closet (this seems ridiculous but I've done this thrice because I like tight spaces).

If you've gone to college, whatever environment you used for study is probably ideal for work too.