==> I noticed that to draw a B or a D, you have to use both straight and curved lines. Maybe that's the pattern.
Hold up, hee haw, whoa ! There are no curved lines, only straight ones, in F and H. That can't be the pattern.
==> I noticed that to go from B to D in the alphabet, you skip one letter (C). Maybe that's the pattern.
Well Hyola ! If you skip one letter in the alphabet each time, you can get from D to F, and then from F to H, and then from H to J .
I'm willing to go out on a limb, bet 3¢ , and state my conjecture that the pattern is "To get from one term to the next term, skip one letter in the alphabet.".
I can't be absolutely positive and say "That's definitely it !". There may be other patterns that can produce the same 5 letters but then not work after that. But the pattern of "Skip-one" can produce these 5 letters, so it's a reasonable conjecture.