Well for me, the biggest thing is that I try not to HO on the merge. After the merge, I've been accused of HO'ing people, but I'm sorry, just because I'm towards the front half of your aircraft, it is not an HO. I don't purposefully ever aim for an HO. HO to me is directly, and purposefully heading towards the gun solution of an enemy, for your own gun solution.
If I have someone on my 6, and scissor, and am able to get enough speed bled quick enough so that the other guy lines up in my guns, I'm taking the shot. Doesn't matter to me where I'm shooting, because by nature, him being 500 off my 6 was the merge already.
When finding a fight, whether or not I jump in is based on a couple of things. If it's 1 v 1, I'll try and vox the friendly to see if he needs help. If it's 2 v 1 with friendly numbers, I'll just buzz on by. 1 v 2 enemy numbers, I'll jump in right away.
I also fly with a wingman on occasion. We generally try and draw one guy low, then hang him up as the 2nd swoops on him. Sometimes if we bring the enemy verticle, for the wing to get a shot, it's an HO. But again, I feel that by him engaging my wing, the merge is completed. I also feel this is not a cheap way to fly, but generally good tactics.
Just my opinion, and since I'm such a n00b, take it for what its worth. lol