Regarding the F1/F12 2+4 string (specifically for first hit of 2+4), here is a quick video I just upped with a few options I like to use (Online Friendly):
Video Combo #1) F1 2+4 Quick Phase D2 (4 Hits 19%) (hold Quick Phase for a sec or you will whiff)...
Notes for Combo #1:
A) If you let both whips from the 2+4 hit, you will have a 5 Hit 23% combo
B) Alternate Combo #1 for an 7 Hit 24%:
F1 2+4 Quick Phase (after first hit of 2+4), SJP 4 Spear Ryu
Video Combo #2) F12 2+4 Quick Phase D2 (5 Hits 21%)
Notes for Combo #2:
A) If you let both whips from the 2+4 hit, you will have a 6 Hit 25% combo which I personally love using...
B) Alternate Combo #2 for an 8 Hit 26%:
F12 2+4 Quick Phase (after first hit of 2+4), SJP 4 Spear Ryu
Only time I use D2 to end is when I am not using Meter to continue the combo.. If I were to use meter, it would be something like this:
Video Combo #3) F12 2+4 Quick Phase 33 EX Spear Ryu, B2 Spear Ryu (12 Hits 32%)
Notes for Combo #3:
A) If you do F1 starter instead it results in 11 Hit 30% combo
B) Alternate Combo #3 for a 12 Hit 33%:
F12 2+4 Quick Phase (after first hit of 2+4), SJP 4 EX Spear Ryu, B2 Spear Ryu