Why is tip #1 helpful? Sometimes too many choices is just overwhelming. Maybe I'm strange but I generally don't look through more than two pages of any etsy shop. I'm really curious about why having 100+ items will make your shop more successful.
Answer:It's because it's next to impossible to get any Etsy search traffic unless you have a higher inventory. For most categories, 100 seems to be the magic number for some reason. (Jewelry actually seems to need more items in your shop for you to start being found consistently, since there is so much more competition in that area).
I really don't know why this phenomenon works, but it does seem to have some truth to it (at least according to the other shop owners on the Etsy forums). Personally, when I have 60 or 70 items, for example, I'll start getting more consistent views but no sales. Once I get 110... 120 items... sales start pouring in. It's quite strange really. I don't know if there's some mathematical reason (like perhaps the Etsy search algorithms pay more attention to larger shops), or if you're just finally able to stand out from the crowd (since some shops flood the searches with 500+ items).
In a nutshell, remember that your competition is everyone who sells similar items as you on Etsy. Some categories have more competition than others. If you have 5 items, and some other similar shop has 5000, when someone searches... that other shop is more likely to be seen... and purchased from.... since they likely won't even find the smaller shop.
Of course there are always exceptions to this rule. I've actually ran across successful shops with 5 items in them. But based on my research, the typical shop does much better with a much higher inventory, mainly just because they start generating decent Etsy search traffic!