As a fellow business oriented GF owner, keep in mind that this is a tool, and if it’s an essential tool to making your business successful, then be prepared for the possibility that it may have an issue that makes your business come to a halt. Have a back up in mind, something like a second laser, whether it’s another GF or another brand. I’m not saying that you could have an issue, plenty of people here who have had their machines running perfectly for years, but they also don’t use theirs for business and can have their machines down for a period of time. You can’t always rely on customer support to get you back up and running within what you would consider a reasonable timeframe, so just be prepared!
With that out of the way, I am a tedious kind of person, so I make a dumb amount of earrings, that’s what I sell most of. Almost every design I’ve made was hand drawn and created using my Adobe products, but there are plenty of places online that have free templates that you can use for your use of choice, keep in mind that you’ll want to look for the ones with commercial licenses! Like evansd2 mentioned, whatever you enjoy making is going to be a good area to start, because spending hours upon hours on something you don’t like will make you resentful of the item. There are so many different directions you can go with, you wouldn’t believe it!
Another important thing is managing expectations. Just because you love an item you make, doesn’t necessarily mean everyone your trying to sell to will care as much as you do. There might be craft shows you go to and sell nothing, or there might be weeks between sells, that could happen for a various amount of reasons. There definitely isn’t a sure fire way that I know of, but learning your market and what they’re wanting is a great start