Cut your fish into manageable pieces. There's no perfect size here, just make sure you'll be able to flip them easily.

Set up a station so you can work fluidly from fish, to batter, to pan, to cooling rack.

Heat/manage oil. You'll want a good amount. Enough to come at least half-way up the side of your fish. You'll want this hot, but not so hot that it burns or smokes. For each batch, check to be sure you have enough oil. If you add oil between batches, allow it to heat up before adding fish. If you're oil seems to have gotten too hot, you can add a bit more oil to cool it down.

Batter, cook, and rest your fish. You'll do this in batches, filling the pan, but allowing room for each piece.

Drop each peice in the batter, move it around so it is coated, ease it into the hot oil with tongs to avoid splashes (careful, oil is hot). Once in the pan, if needed, you can use a spoon to carefully add a bit of batter to the top of any piece that looks a little light on batter. Watch for the batter to puff up and brown on the edges (approximately 5 minutes, but time depends on size of fish, heat of oil, etc.). Using a spatula, peak at the underside. When browned, flip. Cook the next side until browned (this usually takes a bit less time than the first side).

Remove cooked pieces to your cooling rack or paper towels. This helps any surface oil drain off so they won't be oily and will be nice and crispy. If you're making a lot, you can serve in batches or, if serving all at once, you can place early batches in a warm oven while you finish the rest.