Fountain pens are like ukuleles, there are some brands that work out the box and others that need fettling by a professional before they sing. Similarly, when you buy used, you get a bargain but you may not get the writing experience you want - and conversely a used pen is sometimes worn in so well that it writes amazingly. So the same advice is always true - try before you buy.
But with these times being what they are, you may be stuck with ordering online and trying them out. So my suggestion would be to stick to reputable brands - e.g. Pilot, Sailor, Lamy, Pelikan, Parker, Montblanc. I would further say that to have the highest chance of perfection out the box, a Japanese made pen is your best bet, i.e. Pilot and Sailor (and Platinum). Also stick to the same ink brand as your pen to begin with - they are after all designed to work with each other. Then there's the nib - steel vs gold (and here's where prices go from sub $100 to well over $100 and beyond). There are also titanium nibs are rarer but some prefer. And the nib size and flex - fine, medium, broad, stub, soft, hard etc etc. If you have no idea what you'd like then you really should go find a pen store and try them out. Montblanc stores have a neat setup where they have identical pens with all the different nib sizes for you to try and find which one you prefer.
When it comes to paper, you need to find paper that reacts well to the ink/nib combo. Some paper works well with some inks and horrible with others. Since paper is relatively cheap, I suggest you try several out. Moleskin is fine but check out Rhodia (my personal favourite and all I'll use given the choice).
Sorry for not giving you a direct recommendation - it's a hard thing to do without knowing your preferences a little better. So the best advice I can give is go join the forums at fountainpennetwork.com where you'll find much more insight.
