go with what sysop noted first...
do you have everything extending out boom and dipperstick and bucket? if so try and bring everything closer to you,
if you are using a wide bucket on hard compacted more so dry ground, you may not be able to bust through initial couple inches, on the surface easily.
a tooth bucket and less width of a bucket, more likely to breakup and dig down easier.
it takes some time to learn to move boom, dipstick, and bucket all in one motion.
RPM's of tractor, for myself i rarely go above 75% of RPM's, and prefer a lower RPMs, kinda of a high idle, it is a little slower, but it allows my accuracy. i still get all the same pressures at running at PTO rpms. once i get warmed up and things start clicking, i may raise the RPM's on the tractor to meet my own abilities, but again i try to avoid high RPM's when operating backhoe, it makes things to "jerky" causing tractor to bounce around some. *shakes head no* not with a hole i can flip over into