You should start with a fruit that you or your family personally like for your first jam or jelly. There are fruits that are more forgiving than others. Strawberry is one that comes to mind. You really only need a pot, sugar, pectin, and an old-fashioned potato masher. Strawberry jam sets up quickly so you know if you “did it right” within a few hours.
I wouldn’t recommend that you start with a citrus marmalade or apricot since it can take weeks to set up. Blackberry and raspberry have lots and lots of seeds and until you get a food mill or strainer, you may want to stay away from those kinds of fruit.
Blueberry is a good choice. You can make jam and jelly out of those. I generally put them through the food mill but you could easily use the potato masher a little and make some wonderful jam!
If you are worried about the amount of sugar required in full-sugar pectin, you can use no sugar pectin. I have personally cut the sugar back 1 full cup for the full-sugar recipes and had great success.
Whatever you choose, make it your favorite because it will compel you to try more!
Check out my two Nano Canning Cookbooks for great small batch recipes!