How to get sharp photos?

I'm trying very hard to get sharp photos. I guess you can look at my deviant art page for some of my photographs http://thedotisagenius.deviantart.com/

When I go out to shoot photographs I come home with a photograph that gets worse in guilty the further I zoom in.

I want to be able to print the photographs to hang on the wall. A decent sized poster for somebody to have on their wall at least.

I have a Sony A6000 if this helps with a power zoom kit letns 16-55 that came with the camera
I also have a Nikon D5000. Also kit lens 18-55.

There's NO reason that you can't get tack sharp images using either the Nikon D5000 with 18-55 mm lens or the Sony A6000 with the 16-55 mm lens.

I have to assume that you are hand holding the camera since you are complaining about sharpness.

Look on page 30 of your user manual to see how to hold your camera to provide the most rigid support. Holding the camera with only one hand or attempting to use the camera at arm's length will ALWAYS add blur to your shots unless you can shoot at 1/4000th second or faster.

"… Worse in guilty the further I zoom in…" Since you are using a zoom lens, you WILL see more movement (blur) when using the lens at 55 mm unless you are using a high shutter speed and are holding the camera correctly.

With time, you can hone your camera holding skills so that images shot with much longer lenses will not show any blur at all

Here is a link to such a photo. 300 mm f/2.8 lens, ISO 3200, shutter speed 1/500th second with the camera held against my eye and cheek.

Since your goal is to create posters, you need to also make sure you are shooting in 14-bit RAW or 12-bit RAW if your camera does not support 14-bit RAW.

And you are 100% right. You have to have very sharp photos in order to create poster size prints. When I'm shooting for posters, I use an ISO of 200 and stop the lens down two stops from wide open. This lens aperture produces the sharpest images.

What that means is that when shooting outdoors in full sun, I sometimes have to use rather high shutter speeds with I have my 12-24 mm f/4 lens on my camera with the lens aperture set to f/8 (two stops down from wide open) at ISO 200.

This is all part of what you probably already know since you have two fully adjustable cameras from different makers (oh, how I wish I had money to burn… I might be tempted to add one of the new Fujifilm X-T10 compact ASP-C cameras to my collection).

When you say "worse in quality the further I zoom in" - if you zoom in more than 100% then any photo will get blurry. Don't obsess about zooming into your photos - only pixel peepers do that. After checking the photos on your devianart, I can see no problems with sharpness at all. When you prepare an image for printing, you should really be applying sharpening in your image editing software - same if you are putting images on the web, a degree of sharpening is often required, especially if you are resizing images for a web page.

For the best results from your cameras, shoot RAW, apply noise reduction and sharpening in post prior to export. Also, for landscapes don't be tempted to shoot with the lens aperture wide open, lenses are sharpest stopped down a couple of stops from widest. On the other hand, don't be tempted to stop down more than f/22 or you risk diffraction problems which will impact sharpness.