Definitely get a logo. Also get a new theme, it's worth springing for a premium WP theme. I would get a less distracting background image. Some images within the post content would help, maybe post thumbnails.
Good job, a lot of content on there, I like how you also have some videos. The e-mail subscription is also a nice feature for keeping your readers coming back.
Could use a more clean header banner the one being used is low resolution and pixelated also might want to use a background that doesn't broadcast that it is a free image from another site for a more professional appearance.
nice job guitar is awesome i can bar but have trouble cause i never learned scales!!! my only 'issue' with your blog (it's a personal thing so pls don't take offense) is that i find the neon green large guitar background to be a distraction. like i said, it's a personal preference and what you like is really what is important all the best!
great info you have there, with lots to offer for everybody, might be better if you could break the posts into excerpt previews that leads into the full post page so you do not have so much content on the main page, also not so keen on the background ... but maybe thats just me