Here's four swim drill sessions: 600 - 750 - 1000 or 1250 yd swim sessions. Focus on form and technique in at least one session a week. Not sure how to do these? Then attend a swim drill session where proper technique will be demonstrated. Speed will come as you master technique and build swim strength and endurance. We'll target speed in other threads.
Here's brief definitions of these drills:
Build= build within the swim, i.e. Build means start off easy, and get faster as you cross the pool, ending in maximum effort.
Catchup - taking stokes about 3/4 of the way to touching your other hand before each recovery.
Fists - Swim freestyle with your hands in fists
Finger Tip Drag – Drag your finger tips through the water on recovery. You will need a bent elbow to do this properly.
Shark Fin - While kicking on your side, extend one arm. Slowly point elbow of trailing arm up towards sky, hand almost touching your side, making a “shark fin.” Slide hand back down, breathe, repeat. Use fins to start until you master the technique.
Torpedo - Push off from the pool with arms in front of you, like a torpedo. Kicking hard, swim as far as you can without taking a breath, then continue in freestyle, keeping the strong kick across the pool.