Top lane is a very interesting matchup in the current meta. Sometimes you're left on an island to take care of yourself for the first 15 minutes; other times, you get random, often inexplicable, attention from the junglers. The lane is long, and the current meta heavily favors champions with strong sustain or trading capability (generally in the form of shields). It's a position that has evolved to favor tanky champions with strong initiates or game changing ultimates, and so often plays a vital role in team fights or, alternatively, has the added responsibility of knowing when and how far to split push.
Here are some tips to make your top lane experience a little more pleasant.
Start With A Ward
Unless you know your jungler is going to gank top early, you need to start with a ward for any kind of safety. On top of that, you also want to consider the enemy jungler when deciding when to place it. For example, Lee Sin on red side will often start Wraiths, Red, and then gank top at level 2. That means that your ward needs to be down before 2:00 to be effective, so you can place it early on and still get the benefit of the early protection.
On the other hand, jungle Hecarim often does a full clear and always starts blue, so a red side Hecarim likely won't gank top until 3:00 or later. If you place your ward in the first minute, you could very well have it expire before the Hecarim even shows up.
Don't Push Unless You Have Vision
The most important lane for lane control is probably top lane. Because of the length of the lane and the relative isolation, your lane positioning will be critical in deciding how vulnerable you are. Generally, you shouldn't push your lane unless it's necessary and safe.
When is is useful? If you're trying to set up a lane gank (a gank where your jungler comes into the side bush from behind you), you need to push the lane for a bit to deny vision. Also, if your opponent backs or dies, pushing the lane to deny creeps is critical.
If you're a better pusher than your opponent, pushing them under tower to stress their last hitting can be valid, but you need to have excellent vision in the river and have a good understanding of where ganks will likely come from. For example, if their jungler is Zac, he can easily gank you without going through the river if you push to tower, and you should keep this in mind when positioning yourself.
Learn To Freeze The Lane / Learn How To Break Freezes
Freezing the lane is a important skill for any player, but it takes on a critical role for top laners because of the necessity of lane positioning. Freezing the lane is when you get the creep waves to be exactly balanced at a specific, unmoving spot.
The most frequent way to do this is to body block the creep wave at the point you want it. You'll see pros do this very often just outside of turret range. This leaves their opponent as exposed as possible while ensuring that your turret doesn't make creep farming difficult. At that point, you want to last hit as carefully as possible and do absolute minimum damage to maximize the length of time you can keep the wave there.
One thing that people don't understand is how creep waves work and how freezes get broken. If you are last hitting, the freeze will eventually break because your wave (plus your own damage) is doing slightly more damage then the other wave is. This is critical when trying to break a freeze. There are only two ways to do it: Either do so much damage that you remove the entire enemy wave and allow the waves to reset, or reduce your total wave damage (you plus your creeps) below your opponent's wave.
For most champions, the second one is actually the easiest. Focus on last hitting only creeps that are about to die; sometimes people last hit on creeps that aren't currently being targeted, which tends to push prematurely. You may even have to miss some last hits to do it, but giving up two last hits in exchange for your lane moving back to a safe position is a worthy trade. While you're missing those last hits, you can also focus on trading hits, which can also work to your advantage.
The worst thing you can do is fire a periodic AoE spell to clear some minions. This will make the other player's job of freezing incredibly easy and you'll find the lane continuing to stay in a dangerous position.
Run A Few Different Rune Pages
If you're playing top lane as a primary position, you probably need a few rune pages. Depending on how dedicated to top lane you want to be, anywhere from 2-8 rune pages are needed to have just the right combination for any given match-up. Typically, they will look something like this:
AD Full Tank: Armor pen reds, Flat Armor yellows, Flat MR blues, Move Speed (or possibly health) quints
AP Full Tank: Magic Pen, Flat Armor, Flat MR, Move Speed (or possibly health / AP)
AD vs AP: Armor pen, Flat Health, Flat MR, Move Speed (or AD)
AD vs AD (mana): Armor pen, Flat Armor, Mana regen, Move Speed (or AD)
AD vs AD (no mana): Armor pen, Flat Armor, Scaling MR, Move Speed (or AD)
AP vs AP: Magic pen (or possibly hybrid pen), Flat Health, Flat MR, AP
AP vs AD (mana): Magic pen, Flat Armor, Mana regen, AP
AP vs AD (no mana): Magic pen, Flat Armor, AP, AP
Other combinations are possible as well. You don't need all of them. In fact, you can probably get by just fine with the first two if you play top lane only occasionally. On the other hand, if you're the top laner for your team, you need more variety than that will provide.
Consider TP Over Ignite
TP on a top laner is becoming the norm. If you have good map awareness, it can even work in solo queue. The trick is to have a good idea where the wards are on the map and pay attention to what's going on. Teleport gives you so much map presence and mobility that it can be game-breaking late game. It provides split pushing opportunities that wouldn't otherwise be possible, and it allows a quick early-game return to lane that can save you a lost minion wave.
That's not to say Ignite is a bad spell. If you feel like you can abuse your lane with an early kill, take ignite. But if you want to have a farm fest or think you might lose your lane, teleport is going to give your team a lot more options later in the game.