I've been on water for about 10 years now. One thing I highly recommend is getting a plug for a power supply that jumps the 2 pins so you can use the PSU for running the pump and making sure everything is nice and sealed up before ever putting power to your system. Or buy a external 12v power supply to run things, which is sometimes nicer if the unit has a selectable voltage switch like mine going from 3v, 4.5v, 6v, 7.5v, 9v, 12v. That way you can test fans at different speeds or run your pump a little slower when filling the loop so you can add coolant as it pulls it from the res and you don't have to keep stopping to fill.
When taking off stock coolers, just TAKE YOUR TIME and BE CAREFUL!! Make sure you don't stress the pcb and just snug the screws, you aren't locking down a wheel to your car LOL. Test your blocks fitment FIRST before final mounting. Use some cheap TIM on the spots where it calls for and after cutting the thermal pads to size, use some left overs in small piece's on the places it calls for, then mount the water block lightly and then take it off and see that everything is making good contact. You don't want to smoke something because a block was made wrong and doesn't cool part of your expensive gpu's. This can save you a lot of headache and also will end up giving you the best thermal performance in the end. You won't be wondering why your gpu is running at 55c when you see others with the same stuff running at 35c
Soft tubing, make sure you don't kink it!! That will never play well. Always make bends with the tubes natural bend from off the spools, that will help not kink it. Heat up a cup of water in a microwave if you need and soak the ends of your tubes before trying to fit over your fittings. Sometime it's hard to get them on and if you put a cpu block on and then try to press the tubes on the fittings you could be putting lots of pressure on the cpu socket and damage it, bend pins, or worst. I always make sure to at least soak those 2 ends so they go on nice and easy. Only need to soak them for 10sec or so and you'll be good, you don't want the tube to turn into a mushy mess and then not seal lol. Measure TWICE, cut ONCE, will save you money. Start with your longest run and work your way to your shortest, you will use less tube that way and if you cut something a little too short in the beginning, you are likely to be able to use it next on a shorter run.
DO NOT USE TAP WATER for coolant, buy some distilled water. Around me you can get a gallon of distilled for $1 - $2 at a local store. Don't use food coloring for dye lol, it will grow bacteria and then you'll have issues. Buy good additives or coolants that are proven to be good.
Follow some good practice's and you will love water cooling. Once you see the after effects, you will never want to be on air again, no matter how many fans a company puts on their aftermarket coolers. I have been on water for around 10 years like I said and it's the best thing IMHO. It's a lot of fun once it's done and you see the results.
Moral to the story, I HAVEN'T DAMAGED A THING