I had originally posted this as a response on Boards.ie, but guess it's worth incorporating here:
My coach actually gave me most of this advice but I think it’s worth mentioning.
• That when practicing techniques, it is not about the finishing move, position has to be earned, the guard must be maintained and dynamic. Tell your partner to let you know if you’re waltzing up, by jabbing your forehead etc.
• If practicing a technique and someone is being a dick, countering what they know is coming, then change from what you’re practicing, and send them to the floor, deal with awkwardness, as you’d deal with a live opponent. Won’t be long before your training partner sees sense. And it will help you learn how to follow. Your coach if he’s any good will recognise what’s going on, so don't worry about not doing the technique, when I see it happen I congratulate the guy for applying intelligent force against the awkward prick.
I used to do this myself years ago, to a particularly annoying heavy weight, “he didn’t like to be thrown”, and every time he landed he complained: “that’s not the throw!” Eventually he learnt he was going down one way or another, if he knew what was coming, he could prepare his landing; if he countered he got hurt!
• First fix the eyes on the heart, it tells the truth. Learn how to recognise a throw, kick or punch from here, don’t follow the limbs. When this is internalised you can start to play with faints and draws, gaze down and strike the head etc.
• Fighting is minimalism, always think how I can minimise the chance of failure, and maximise the chance of success. E.g. parrying, blocking, locks etc. don’t use your hands, learn to use your forearms.
• AVOID BRUTE STRENGTH. If the only way a technique is working is through great effort, then you’re doing it wrong, I see this in locks over and over again. Beginners not understanding leverage, trying almost to crush a limb, rather than using a see-saw lever effect. The danger for their partners is of course, that the fools develop a kind of inferiority complex, always employing retard strength, so, if or when they actually do get how to do a lock, applying such force could seriously fcuk up their training partner. NOT COOL!!!
• Related to the last point, just because someone is a heavy weight and you’re middle weight does not mean they can be used as a punch bag. It does not give you the right to apply all your power in a strike, throw, locking technique. First, if something isn’t working, ask yourself, am I doing it right, or is there something fundamental I’m missing here? Don’t assume he’s bigger, so I’ll put down the shot gun and use the thermo nuclear missile. Most heavyweights I know put up with a lot of **** that they simply wouldn’t take from someone of equal weight, because they don’t want to be a bully. Lightweights don’t confuse this for success!!! If he’s taking your full force strikes and not complaining, it’s because he sees you as a pathetic little prick. He wouldn’t hit a old woman, and that’s why he’s not knocking you out!
• Cleanliness: Cut your nails, after years of ripped back and limbs, infected scrapes on my neck torn soles on my feet etc, I’ve started banning people for two weeks for such offences. It’s the highest form of disrespect in a martial gym to carry on like this. And a guaranteed way to piss everyone off. On a lesser more forgivable note, if you find that you have bought some crap gloves or shin pads etc. that keep scraping / cutting your sparing partners, ask your instructor for advice on where to source good equipment.
• On that note invest in good equipment, i.e. respect yourself and others, prevent needless injury.