Had my first Magic: The Gathering games yesterday: Any advice for newbie?

[robvalue]

I'm a bit out of the loop with card selection, but I would recommend going with something like 20-24 lands in a 60 card deck. Oh, and always make a 60 card deck, if you're playing to win. It improves reliability, and the chances of running out of cards are usually negligible. How much land to use exactly depends on the mana cost of your cards, the higher they are, the more land you'll want. If the number of each colour card you have are fairly equal, you can split the lands between the appropriate types. If one is dominant, or especially it has a lot of multiple mana symbols, you can favour that kind of land.

Make sure you have ways of dealing with creatures by either killing them or screwing with them, and also dealing with artefacts and enchantments if the colours permit.

You also want some sort of curve, so that you expect to get stuff going as you lay your lands down. This doesn't mean you have to have something of every different cost, but don't make a bottleneck deck where nothing happens until you get to 5 mana say, and then your hand is clogged up with loads of cards you don't have time to use.

I made a strategy guide for playing tips regarding the Duels of the Planeswalkers series a few years ago, if you're interested I'll find the link Most of the hints will apply to regular magic, although Duels is somewhat simplified.