I was looking at the wood on your website and everything I saw was still in diagonal format. I think the advantage of diagonal is capturing 3 sides vs standing vertical you're likely only capturing 1-2 sides.
I'll just comment on diagonal and I'm gonna go a bit nerdy but here it goes... If you want to make diagonal work, it's all in the lighting. The reason why some of the shots are blurry on the front end is your depth of field is too narrow. You have to shoot the photo at a higher f-stop like f10+ depending on lens/distance.. You can achieve this one of two ways:
1) Boost the power of the light source Let in as much light as you can through windows, and you can also use a light reflector for shaded areas like the top of the block. You can find light reflectors at photography websites, but really even a silver car shade or white posterboard would do.
2) Lengthen the exposure time. You'll need a tripod and shoot in manual mode. Set the ISO around 200-400, f10+, and play around with the exposure time til you get what you want.
Not sure what you use to process photos but I highly recommend Lightroom. Shoot in RAW format and learn to edit the photos. Lightroom 5 is really awesome because it allows you to adjust exposure for the entire photo or parts of the photo. People think using too much lightroom or photoshop is cheating somehow.. but in the case you are trying to sell a piece of wood by showing grain structure you need to bring out that contrast. Given the way cameras meter lighting, its often very hard to capture the contrast your eye preceives unless you have an ideal lighting setup. (Just think of the last time you tried to photo patina on a knife)
Last thing as others said use a tripod. Repeatability is the key!