I (almost) always sample an ink before purchasing a bottle. Part of this is just economy. Part is because I like to try several different inks that are very similar to each other and choose the one I like the most. Part is because I am an ink addict and I like having a hundred ink sample vials in my desk drawer.
When I have decided to make a commitment to buy a bottle of ink, I am always filled with anticipation. I select a specific pen or two, clean it out and get it all ready for my new ink.
When my ink arrives I take time to admire the bottle, then ink up one pen about half way. I have an ink journal where I draw a little rectangle and fill it in to display the color of the ink, then I write the ink brand and name, then the pen and nib I used.
After this I test it out on lots of different papers. I have test papers that I keep around for specific colors and papers for whatever inks I am using that week. I compare the ink on the different papers, and if I love it (which if I bought a bottle I am already sure of a growing affection), then I ink it up with another pen. I always look for the perfect ink + pen + nib combination. I like to know how an ink will look in my different pens and find just the right match.
I prefer stub nibs or the Ahab flex pens because I can see more of the ink; shading, flow, the depth, saturation, hidden qualities and hues are easier seen in big wet nibs. I also just really love stub nibs.
After testing on different papers, I will use it until the half fill runs out. I write in my journal daily, I write a lot of letters, I write in my devotion time, etc. I am a writer so obviously when I am working on one of my books I can use it then too (although I usually prefer an ink that corresponds with the mood of whatever I am writing).
I like to compare the inks I have with one another to see the themes and stories they tell. I lean towards similar inks in a variety of ranges - most of my inks are purple, pink or turquoise; but I have other colors as well. I like to draw flowers and get a feel for how the ink works in a picture. (Although I am not an artist at all and my drawings are pretty sad looking, it is simply for my own amusement.)
One thing I just started trying is seeing how the inks work with painting and color washes. I am having so much fun with this new experiment. It is fascinating to see how inks perform and transform when interacting with a paint brush and water! (Be sure to use good paper if you do this. Thick watercolor paper is great. I've been using Tomoe River a little too, just don't get it too wet.)
Most of the time I want to use several different inks in different pens every day. I like variety. But there are a couple inks I almost always have inked up in a pen. I suppose it really depends on how many pens you have and how often you are willing to clean them out, lol. Most of the time I won't do a full fill on my pens. I know I will want to switch around the inks I use.
I hope you enjoy playing and having fun just writing with your inks & pens! There are so many lovely choices available!