Actually, EQ and compression is about the last thing I mess with when designing one of my sounds. That's just the final process when you already achieved the sound you're looking for and you just want to sharpen it up and mix it into the rest of your production.
I don't know what equipment you have, but if all you have is just a mic and a DAW with only a couple plugins, you can only do so much.
I recorded a shoe last month and turned it into a pizicatto string synth. But that was with the help of my Fantom.
If you have the right tools, you need to learn about filters, cutoffs, resolution, attacks and release, portamento, tuning, velocity, LFO's, wave forms (Triangle, Sine, and Saw), your basic fx like chorus, reverb, delay, and panning.
If you're lucky, you have some equipment that can do all of that in layers. If you have 2 sound layers that's cool, but if you want a more developed, realistic sound, I'd reccommend 4 layers. I think the Yamaha Motif ES and XS is capable of 8 layers...I could be wrong.
But keep in mind the more layers you have on a sound, the more poly it's taking up. So instead of hitting one key on a piano, it's like hitting 4 keys at the same time if you have 4 layers. I think standard poly on a lot of hardware is 128? So if you're instrumental is full of patterns and layers, you might start hearing some sounds drop out.
The Fantom is capable of allowing its user to decide the order of importance of each sound layer so that if too many sounds are going, the least important layer drops out so it still sounds as good as possible.
You could always go with just recording a random sound in your house, but unless you learn about those things above, it's probably going to sound exactly what you recorded, or worse depending on your equipment.
The easiest way, is to find a sound you already have or a stock sound similar to what you are going for and then edit that sound to your liking. Mess around with all of the things I told you about and learn what each thing does. In a week or two, you'll be able to hear a sound and be able to know in an instant what you want to change to it. If you need some help let me know.