I use melodyne(to change from major to minor or vice versa) or pitchshifter for pitch and timestretch for timing. I often microchop a sample and then roughly quantize it so the overlaid drums sit perfectly. Music recorded live doesnt have a fixed tempo and because of that you get humanised grooves, a downside is it takes some work getting everything to play nice together. Take all the time it takes to clean up timing issues at the start before moving on, this can save a lot of clean up work later on. Chopping on the zero crossover points of the samples is very important to prevent pops and clicks .
Basic loops can get a bit boring after a while, so to keep things interesting, repeat parts of the loop at key moments, chop parts and shift them around. Just adds a bit more interest in what could become mundane quickly. Its always about keeping things interesting, subtle changes, fills that come in unexpectedly, but tastefully, keeps a person interested.
Its most often best to sample in mono as this gives greater control over where you want to position things in the mix rather than have the sample decide. Choose the best side (left or right)that has the best version of the part you wish to use.
For example for a bass line I will often take the original samples bass from the strongest side, and put a low pass filter on it at around 200hz or below, give it a bass boost at 60hz and then have that as its own layer, which I can sidechain a kick to, to control muddiness. I will take further chops, take the bass out of them so it crosses over with the bass, then layer those over the bass, panning them where I want them, and filtering(eqing) as I go.