You're using 120? If you spoil a film, then don't throw it away. Keep it in the backing paper and use it for reeling practice in light. I personally use a film changing bag - I know its not the perfect solution, but it works for me. As already said - wash your hands, keep cool if it goes wrong. I carefully roll the paper first, feeling for the start of the film, then roll the paper and film apart. Tear the tape, then feed the rolled film onto the Paterson spool. I avoid touching the inside and also the edges. A tiny bit of sweat on film edges can make some films on some reels stop. Try not to buckle the film if it does jam. It will damage and appear as crescents across the images. Either start again, or if it is a Paterson type, try finishing it off by tiny little shuffles of the reels until it completes loading on.
I use a large bucket for rinse water, and I place my chems in bottles in it first, to correct overall temp. Totally agree on not being too worried if the temp is not exact. C41 is fussy, but b/w process is quite tolerant. I aim for 18.5 C to 21 C. I confess, I've successfully developed without a thermometer.
Important parts are develop, fix, and rinse. Keep your chems well labelled and stored. B/W processing at home becomes very cheap once you've mastered that.
If you process in a bathroom, then hanging films to dry works really well and dust free, if the bath or shower have recently been used. Dampens down the dust in the room.
