Thank you guys, really. I've never thought of playing Sona, but my friends have told me to check out Taric, and to keep an eye out for Thresh. I will definitely keep all of this in mind.

You'll probably always struggle with a new champ the first few times you pick them up. I'm at level 30 now and picked up TF yesterday. The first game went well because the opposing mid wasn't very good but I got destroyed by a very good brand in the next one.

Generally the best thing to do is find a guide for the champ. You don't have to follow it verbatim, but it can give you an idea of what to max first, what to buy and how to play them. Keep at someone you're interested in, and sooner or later you'll be just as good with them as you are with Alistar.

As a relatively new player myself, I am still learning the champs and their abilities. I have my favorites (Darius for top lane, Annie for AP mid, Fiddlesticks for jungling, etc.), but I do try to set aside some time to play each free-to-play champ in a custom game vs. bots. This helps me figure out if I like playing them and helps me understand their abilities so I can better counter them in normal PVP matches. Custom bot games are also convenient because you can experiment with combos without upsetting teammates and quit the games without penalty after 5-10 minutes if you have to.

If I find a champ I like, I search out guides on Mobafire, LOLKing, etc. I then practice against bots to get the timing, combos, and moves down. From there, I try to spectate a few games where I see the champion being played. After that, I may hit a Co-op vs. AI game or go ahead and try my hand in a PvP match.

Obviously, all of this depends on the amount of time you have to commit to the game. Best of luck to you, and I hope you find a good ADC or bruiser that suits your play style. They certainly are a lot of fun!

P.S. I highly recommend spending the $5 at Gamestop (if you can) to get the starter card. It unlocks a set of champions and gives you an IP and XP boost.

Little bit of advice from somebody that was stuck in the same situation.

As Alistar is support you need to completely change the way you play. My suggestion is to play either rengar jungle or darius top lane.