I could use some sampling help...

So i've been messing with my 500 for about a month and i'm starting to get the hang of it. This is my only piece of hardware and i've been using Audacity to slice up some samples. But it seems like when i try to adjust the pitch it sounds kind of dull and lack luster. I've been listening to some of the beats from you guys on sound cloud and there the dope shit i'm trying to make. I just need some tips to sharpen my skills and make better music. Any help at all would be appreciated!!

Thanks, i'm thinking of investing in a turntable so i can do some real digging for rare breaks and loops, do samples sound better of vinyl in general or is the difference barely noticeable?

Vinyl has a few advantages, but not a must.

Most vinyls have a proper sound quality (except for those cheesy compilations and greatest hits and stuff).
At least, most of the time the quality is better than most mp3's.
But cd's also gives u great quality of course.

Another plus is that u can find some dope ass stuff on vinyl's that cant be found on cd's or mp3.

Personally I prefer vinyl because it also gives me more control. Pressing some buttons and tweaking some sliders to shape the samples before going into my mpc. Or just simply speeding it up on the tt before sampling can also come in handy.

Don't stress on the beatmaking. U just started out on the mpc500. There are no specicific top three tips that will make u a good beatmaker over night.
Read all the tips, watch youtube and experiment. Some things u probably like as part of ur workflow, and other things not. U can only find out by trying it out. And once u do like a certain technique or something u have to master that technique and make it your own.

Practice, practice, practice