SMD diodes with mark YR103, WX104, and RZ102

1. KT3 is a BAS21 diode. Link goes to the data sheet, includes information on similar diodes (BAS19/BAS20/BAS21) and the date code (yours seems to be July 2007)
2. CVL seems to be a transient voltage suppressor. The link goes to a site with lots of SMD codes.
3. A48 could be one of several things. You'll need to compare the connections of your chip to the datasheets of the various parts that may be marked A48 (most likely a voltage regulator.)
4. 1PX looks like its a voltage detector.

For the 1PX, the dot shows pin 1. Putting Pin1 at the lower left mean you read it 1PX instead of other combinations you tried (K and stuff.)

Sorry, I can't give you any really good tips for finding the codes.
The linked site helps, and there are others like it, but it all comes down to having good google-fu.
Google, get ideas, check the circuit against the datasheets.

I'm surprised noone mentioned the various SMD codebooks [for active components] one can find a google search, e.g. the largest seems this one. I've identified fairly obscure Ricoh chips [voltage regulators, low-voltage detectors] and run-of-the mill SMD transistors using that. Because the codes are not unique, it helps if there's more than one component from the same manufacturer on the board and also if you have some clue what they do in-circuit. For stuff found in a junk storm, it might be harder.

The best general document for identifying SMD passives I found is Wikipedia's SMD page and this IAEA one. I suppose you know SMD resistors have standardized codes. Alas no codes whatsoever for ceramic SMD caps, so you have to ultimately measure them. There is a rough relationship with color and size, but I was never able to find a certain one. Wikipedia proposes some ranges for each color (alas without any reference), but the ranges are pretty large and overlap. The tantalum SMD caps are marked though. Inductors are just as bad as ceramic SMD capacitors when it comes to marking (and the THT inductors, unlike THT, caps are just as bad.) Coilcraft uses a color code for theirs (above 0603 size), but I haven't seen it adopted by others. The thing you can be fairly certain of is that SMD inductors are likely to be black and the capacitors more likely to be light grey or beige/maroon, as you probably know already. Also inductors are usually magnetic.

And that's all I know, as the saying goes.