OK, lets start from the beginning. I don't have any experience with Ilfosol3, but you'll be able to learn from the general rules.
First thing is development. Since you're using a color enlarger, this means that you have a diffusion head. These are great for minimizing scratches and dust, but they are also of a lower contrast than condensers. This means that you have to develop negatives so that they are a bit more contrasty than for condensers. You might have to overdevelop them a tiny bit.
For enlarging, you have three factors:
-time
-grade
-aperture
For aperture it's simple: your lens is at its sharpest about 2 stops from its maximum aperture (usually 5.6 or
. So you expose at that aperture.
For time and grade it's a bit more complex.
The time depends on the paper, enlarger height, aperture and filtration. Since you have a negative, it means that the blacks are set by the transparent parts. So exposing for those is a good start. The clear parts of the film should give the densest blacks.
When you do a test strip, forget the 1,2,3 second thing. It's better to do them logarithmically. I know it sounds complicated but in reality it isn't. Just expose the whole strip for 1 second, cover a small strip to make the first stop and add 1 second to the rest. Now move the card and add 2 seconds, move and add 4... and so on. You'll notice that the first block will be 1 sec, second will be 1+1=2, third will be 2+2=4, fourth will be 4+4=8... and so on. A perfect log progression. Why is it better? well, your camera works in the same way both speed wise and aperture wise. One block will equal 1 stop. Easy.
Now when you expose the first print, it's easy to know what to do. Print is too light? Add one stop exposure by doubling the time. Too dark? Remove one stop by dividing by half. And so on...
The paper can only record about 9 stops variation, so the possibilities are quite limited in a way.
The printed image is still dull? Then you might need to change the grade. The enlarger without any filter should give you a grade 2. Add yellow to make the print flatter, magenta to make it "contrastier". Now, changing grades will change the exposure on a color head. But to make things easier, manufacturers publish in the booklets some compensation factors for different filtration. I made a small sheet with the information and the various filtration/grade variants. I just take the exposure for a flat print and apply the factor to get something at least proper. Rough estimating the values usually work.
If your enlarger doesn't have any information available, you can make a compensation chart using a good exposure meter (regular, not a print meter) and dialing in the various values (no neg in the enlarger).
This is basically how I do my prints. It might look complex but in practice it isn't.
Hope this helps...
