Anyone here bother collecting cards? Any Tips for a noob who until the last week or so barely even bothered to check them?
Ok, I am not a expert (I started to "collect" cards only a few months ago), but I will try to answer your questions.
The cards have no use except to make badges (and to sell them for Steam credit). When you craft a badge it gives you: one badge level (there are 5 levels by badge), 100xp, one background and one icon. The backgrounds can be used in your steam profile (as a wallpaper). The icons can be used in your chat or forum posts. In special events (like summer os winter sale) crafting a badge can give you special things like season cards.
When you extract all game cards, you are eligible for a booster pack. With your Steam level you have more probabilities:
Level 10: +20%
Level 20: +40%
Level 30: +60%
Level 40: +80%
Level 50: +100% (double probability, not 100% prob.)
You can see it here: http://steamcommunity.com/tradingcards/faq
I don't remember where I see that you need a certain level (maybe it is only my impression). I have my first at level 10 (I think). In the past 6 months I see 4 booster packs (I am now level 27 and are eligible for around 400 games).
If you want to trade cards, I recommend you the trade forum of this group: http://steamcommunity.com/groups/tradingcards
Edit: One more thing: to trade for the cards you want, you need cards that you do not want. For example, maybe you don't like this free game for indiegala: Mechanical Escape
, but it have cards. Redeem it, extract cards, unistall and you have cards to trade for your afterfall insanity (maybe 2:1 or 3:1).