I wrote a bit about this in my tips for the recommended deck Size Distortion. But anytime I see Gardens in the supply, I look for cards that will get me more cards. A Garden costs 4 treasure and is worth a VP for every 10 cards in your deck. Thus more is more!

Be sure to buy as many Gardens as you reasonably can. Do not totally clog your deck, but do not shy away from them early either. You may have to be more aggressive if there are 2 or 3 other players trying to buy them. If other players ignore the Gardens then you can get a ton of cheap VPs.

Some combo highlights include:
Thief – Even better with more players as there is a greater chance of getting more cards per turn
Workshop or Ironworks – Both are good for gaining free Gardens
Woodcutter (or any other card that gives you +1 Buy) – Remember you can always get a Copper for 0 treasure with your extra buy.
Pawns – You can stack a few of these to get +1 Action and +1 Buy. Then play another one…those extra Buys can add up quick.

If Curses are being given out they are bittersweet. On one hand they are adding to your total number of cards, but on the other they are taking away VPs. If the Supply has a card that allows me to trash the Curses, I try to count my deck as I play it. If the game will be ending soon and I have some cards to spare, I trash some Curses.