Yours is a difficult question to answer. There's a lot of finess in chiseling. Sounds like you aren't very familiar with it. You probably should practice inletting (something) into some scrap wood.
How I hold, push, tap, or drive a chisel depends on a lot of variables. The bevel angle plays a role, too. If you place the edge of a chisel right on a line and drive it straight down into solid wood, the bevel will push the edge over your intended cut line. You need clearance for the waste wood to go. A narrow chisel will cut deeper with less effort. So will one with a steep bevel. If you push a chisel along the grain, you run the risk of it splitting the wood or worse, slipping and damaging the work. Tapping with a mallet reduces the risk.
A hammer is a poor choice for driving a chisel for a lot of reasons. Get a decent mallet.
It just takes practice for it to become intuitive.