One of the most frequent questions I get asked is what is a good fountain pen for beginners. Being a fountain pen novice myself I have tried out several and always come back to one that I always recommend: the Platinum Preppy.
The reason I like the Preppy so much is that the nib writes very well for such a low cost pen. I of course prefer the Fine nib, but there is a Medium option if you prefer. When you first snap in the ink cartridge it takes a minute or two of scribbling to get the ink flow going, but once you do it is a solid, steady, and smooth performer. I keep this pen within reach at all times for when I want a no nonsense fountain pen experience.
Seriously, for $3.30 from JetPens you cannot go wrong. If you have never used a fountain pen in your life this is a good, inexpensive way to see if you like writing with a nib. If you do like it, then that is where the trouble begins. :)