Okay, I seem to be just the opposite of everyone else on the lighting issue. I prefer dim light, as I can see those dark veins easier, and if I absolutely can NOT see a vein, I somehow think I can feel it better (must be psyching myself out).. Those dark veins just tend to show up better for me in the dim light. Remember, vampires like to work in the dark. Everyone comes into my roooms and flips on the lights as I'm about to poke a patient and I glare at them, then they remember and turn the lights back off. It also helps keep my patients calmer not having those bright lights in their faces. (I work in ER, they're already stressed enough, and usually dehydrated or without veins to start).
One other note, if you're able, try to use some humor... If your patient happens to ask if you've done this before, try this line, "I saw it on an episode of ER once!" I can't remember where I picked this up from, might have even been from this BB, but it works every time!
We all have our bad days at IV sticks... I have a 2-3 poke limit... if I can't get an IV on my patient in 2-3 sticks, I'll go get another nurse, and they'll all do the same.
My final tip... the veins in the dominant arm are generally going to be larger! if the patient is right handed, check the right arm, it'll have nicer veins. I know we always try to put it in the opposite arm, but the better veins are in the right arm! LOL