Does my lens ____ or do my skills?

[Ocean Lotion]

I have a Sony Alpha 300 with which I am using a Minolta AF 28 - 80 macro lens. I have difficulty getting pics to come out in focus and I can not get a close up with the macro function of the lens. Does this lens have a good or bad rep? I read some bad reviews on it on the internet but I know not to assume that means it is a bad lens.
Can anyone recommend a lens I can buy used that would be good for tank shots?
Also all my shots come out blue, what settings would I use on this camera w/o going raw?
Would a blue filter help?
I am not a big camera buff. I can take good pics in high light but always struggle in low light when not taking tank pics.

Help

 

[nautical_nathaniel]

I was having so much trouble with my zoom lens on my Nikon that I switched to a 35mm Prime and it has made a world of difference. It's much easier to get better clarity on the photos. I also use a lens hood that I press up against the glass so that my camera is aligned with the glass to prevent refraction. Doing so also removes any possible reflections that you may have on the glass from other light sources in the room.

 

[Ocean Lotion]

Love that idea about pressing the hood against the glass but I have to have my camera a ways back from the glass to focus in macro. Does not seem right to me.