Coarse fishing's wonderful so where should I begin...
1st) You'll need a rod LICENCE to be legal, along with extra permits as applicable.
2) Think "It's all about presentation" when tackling / baiting up:
You want the thinnest line for your intended quarry (so the fish can't see it - adds greatly to the "sport" value as you might on occasion need to "play" the fish you hook to tire them out, especially if the fish is heavier than the line's breaking strength).
Similarly, you'll need the smallest hook you think you can get away with and be sure to tie a good "proper" knot with excess line trimmed away. Then you want bait that will appeal the most to fish of the species / sizes you're aiming at.
Landing nets are great if you're after decent sized fish and a keep net is useful if you're into the idea of holding onto your catches for a while (say for purposes of competition / using caught fish as livebait / deadbait).
Half of the battle is in learning to think like a fish. Where exactly will they be? Are they feeding (if not, WHEN?)? What will they take? (Err on under-baiting your hooks if anything!)
If using maggots (probably the most popular bait) or earthworms, pick "lively" ones, trying to change your bait on every cast. Worms, you probably want to stab around the half-way mark, whilst maggots should be threaded through their rear ends.
If piking, you'll need treble hooks and wire traces (you tie the trace to the end of the line so so the pike doesn't snap you as it will half the time, otherwise).
Remember, there's no harm in targetting those you've had a visual sighting of! Shades should help you see into the depths more easily on a sunny day.
Ground bait's good in moderation. When you're happy with your cast and have hit a spot that you think you can (and would like to) cast out to again, throw a little bait / groundbait around your float / leger. BE SURE NOT TO OVER-FEED HERE, you want to attract a shoal to the area but you don't want them swiming off well-fed!
Make sure your float is correctly weighted at all times (just the tip above the water) and fish at the right depth. You'll have to work that out yourself: Attach a float and a leger (/ a load of weights) to the end of the line, initially. Cast out. If the float doesn't "cock" (think that's the right word!

), move the float up a little. If it lies flat on the water, move it down a little on reeling in. As you generally want your bait at the bottom (most fish are bottom feeders), you need to get this right. Then replace the ledger/weights with your baited hook.
The idea is to get your bait to sink slowly (ie. "naturally"). So, it's all about where you attach the weights that are going to cock your float. Avoid using one large weight (unless legering off the bottom). Use several smaller ones just above and below your float (to keep it in position), a tiny one around a foot away from your hook and necessary extras somewhere in the middle.
You'll need lots of patience and you should avoid reeling in too excessively (too many casts won't be good for your bait amongst other things). Also, you'll need to develop a good idea of whether your casts are good and the bait is staying on your hook mostly, OR NOT. Replace lifeless bait (unless deadbait) immediately.
On reeling a fish in, you'll need to keep your rod UP to avoid the fish dropping off. (Barbed hooks are illegal nowadays, I think!)
When, casting out, cast a little further than your desired spot. Then, point your rod downwards and gently break the surface of the water with the tip. A little jerk of the rod (with a little reeling in at the same time), should
sink your line, essential so that the fish don't get spooked.
Be as quiet as you can and try to dress in your green and browns for camouflage. You don't want them seeing you and being spooked. Pick up all your litter to avoid potential trouble.
You may need a disgorger for fish that have practically shat out your bait!

The idea is to know when to strike. You'll never miss a perch bite, but roach bites can a pain in the arse.
The more rods you own / take, the more fish you'll catch and fun you'll have.
Gently lower fish back into the water on returning them to minimise their loss of slime (which protects them from infection).
You might wish to take an mp3 player (with earphones), and a cameraphone and a set of scales (for weighing could be good). No-one likes a fisherman's tale without EVIDENCE!!!

Naturally, turn your phone off / put it on vibrate.
And above all else, don't fish in particularly dangerous places / near overhead power-lines etc. You don't want electrocuting!!!

Good Luck and stay warm / cool / dry as applicable.
I'm assuming you're already familiar with taking your reel's bail arm off to cast / when letting big fish "run". Of course, if you know there're submerged obstacles where you're planning to fish, try to avoid letting fish take you were you might get snagged and lose them (and possibly half your tackle!!!).
I think that's 99% of generalities covered. Let me know if you've any specifics.
