I am still a beginner, but perhaps you can learn from my very recent mistakes and confusion.
I use the Ilford filters but trimmed to fit in my tray. I also use multigrade papers.
The advice previously given on one film, one developer is solid. Sticking with one film, one speed, and one developer for months at a time really helped me learn. FWIW, i started with ilford delta 100 and DD-X. Then tri-x with DD-X. Then tried Perceptol, ID-11, Microphen, and Ilfosol 3. I now use Perceptol for my slow films and DD-X for fast.
As for the dimness, I'm not sure how your enlarger is constructed, but after many trials and errors I realized that the lens board and clip in mine (durst m600) had gotten wonky. I took it apart and discovered the clip had jammed and several itty bitty bits had shaken loose. Got it fixed, put back together, and swapped out the grungy old lens and have been faring much better. Also, make sure you have the correct lens for your negatives.
Happy making! - ruby
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