Simple bark graft is what I do with almost all of mine. Dormant scions onto actively-growing rootstock. Have done simple whip grafts with good success, as well.
Biggest thing is aftercare - you've got to check almost daily to keep rootstock shoots rubbed off or they'll rapidly overtake the graft and it will decline and die.

lucky p......what time of year do you find best for your grafts...I have heard summer is a good time but have done cleft grafts with similar size scion wood in early spring with lots of luck on apples and cherry but didn't have luck with the persimmon.......

groall,
I start grafting after rootstocks break dormancy and begin leafing out - and usually after last frost date.
I'm not a huge fan of cleft grafts - have done 'em on stuff like hawthorns that have really thin bark that doesn't 'slip' very well. Bark grafts are quick & easy, scions don't have to be the same size.
Can't stress enough the need for diligent aftercare.

One thing that I would watch is after it takes, to make sure you keep them adequately watered. I have done whip and tongue grafts on my American persimmons and 3 took. However, as I don't graft them until May here, we will get some hot dry days just after they take and if you don't water them even one time, they are vulnerable and can die. Out here in the PNW summer is hot and dry, not wet and humid, so the baby trees can die of thirst. Also, be very vigilant of slugs. Several climbed up onto the scion and they would have died, had I not been out there at midnight with a flashlight. Incidentally, none of my rootstocks outgrew my scions, but that may be a regional effect.
JOhn S
PDX OR