I'm slowly realizing that one of my main problems is I play very aggressively. I'm not the type to shy away from engaging the enemy, and that often will costs me with the squishy types I often play. Maybe it's time to re-think who I play.

What are some champs that can and should be played aggressively, as initiators? The first two I thought of in this vein are Singed and Alistar. What are some other choices that will do well?

Mordekaiser cannot be played anything but aggressive. http://www.leagueoflegends.com/board...ad.php?t=92617 is a great guide to help with that.

I play a semi-aggressive blitzcrank. I initiate by bringing their squishy to us, and that first death quickly changes the tide of the entire fight. By doing this though, I will have to run out mid-fight and heal (because I'm always focused).

Try an assassin, they generally go for a kill, then retreat (great for 1v1s).
Or try any tank, their job is to initiate, and stay in as long as possible for your squishies to burn the enemy down.

Above all else, no champion is invincible. Learn when it's appropriate to run out and live to fight another day.

anivia can play agressively early game since the egg and people dont do enough DMG to kill it so use that to ur advantage for early kills cause i do

Poppy needs to be played very aggressively, since killing people is your main source of income. And she's pretty good at it too.

Like wolverness said, Mordekaiser is king of offensive play.