Victory points are great
They are great when you get them, but are not to be counted on at the endgame. There are seven victory point cards in a 36-card deck in the original (first and second edition) Mayfair version, which means you are drawing an average of five (at a cost of 15 production cards!) to get a point, and ten (30 cards!) to get two. It is much easier to get two points with far less than 30 production cards the old-fashioned way: build something. It gets worse with the Kosmos or later Mayfair versions (five victory point cards), diluting the mix even further.
Don't use knights too early
Save them if you can to keep the robber off of your hexes (play BEFORE you roll the dice in this case). However, don't get caught with too many development cards, as you can only play one per turn. This is especially important if going for the largest army, get those knights out before the endgame.
Watch out buying too many development cards early
If you draw a victory point card (or two) at the beginning, it can really hurt your future development chances, as they don't produce. However, the rest of the cards CAN produce for you (at least indirectly).
Save that Road Building card to the end
If you are going for the longest road, you must try to save the road building card to the end because it can be a great surprise when you play it on the last turn.
It is also great to use at the beginning, to save the four resource cards and pump up that exponential growth rate a bit.
If you can't build anything, consider buying a card if you can.
You will lower your card count and keep the robber away. Also, it is a great way to "store" resources for use later.
How much is a development card worth on the average, just in resource cards? If you assume that a knight card is worth one (from getting one resource from a player), road building is worth four, monopolies are worth three (this just evens the card out, of course you could get a few more or a few less), and discovery is worth two, then each development card is worth 1.3 cards in the (first and second edition) Mayfair deck.
Note: this is true in the Kosmos/3rd edition Mayfair deck as well.] That is for a cost of three. Of course, that doesn't count victory cards, getting the largest army, etc. If you play a resource card at an optimal time, it can be worth a LOT more to you.
It is hard to get the robber off of you without Knights
Remember, a seven comes up only once every six turns on the average.
Know the odds
Your chance of drawing a particular type of card is as follows, in 36-card combined Basic/5-6 Player Expansion set (this is also the same as the first or second edition Mayfair Basic deck):
- Knight: 56%
- Victory point: 19%
- Discovery: 8%
- Monopoly: 8%
- Road Building: 8%
Meaning, your chance of drawing any specific card, other than a knight, is pretty low.
Note: the percentage chance is the same in a 25 card Basic Kosmos/Mayfair 3rd edition deck.