You already know which crafts you love. Popular items change so quickly that it's impossible to go into specific details here, so we'll speak in general terms. You want to sell item(s) which:
Popularity is important because without it, fewer people will want to purchase your item. If popularity doesn't apply, at least try to include practicality. Something useful can be a very appealing attribute to a prospective purchaser.
Speed of construction must be taken into consideration, particularly if you plan to sell lots of items. You'll not likely get get paid fairly for your time if something takes ages to make.
Uniqueness will make a customer buy this item created by you as opposed to a similar item they've seen dozens of times already. Personalized items score high here.
A reliable souce of inexpensive supplies must be found. What happens if you sell very few or no items? You've invested money as well as your time in this. Worst case scenario - you totally lose your investment. Make sure it's not more than you can handle financially.
Your personal enjoyment is often overlooked. Be sure you're enjoying yourself as you're creating your crafts. Remember, you'll probably be putting a lot of time into this. Without the enjoyment aspect, it's no longer your "dream job".
The market has to be there for your craft or it simply won't sell. This is somewhat connected to practicality and uniqueness. You don't want to try to sell fulled mittens on a tropical island, or a crocheted bikini in Antarctica (no disrepect to inhabitants of either intended). If the market is already flooded with a particular item and you haven't come up with a way to make your version so unique that it's a "must have" for buyers, you're probably wasting your time. However, there are some that have had luck with selling items off season - ie Christmas items in the summer. Less competition, they say.
Last, but far from least, are copyright issues, which shouldn't be ignored. Please, respect the intellectual property of others. Seek legal advice before proceeding if you intend to base your inventory on someone else's creative work(s) -- with or without their permission.