My advice before you give up would be to not give up. Some people just aren't good at them and that is ok. But You will learn that you will have good runs and bad runs. Maybe you'll sink 2 or 3 in a row, and then miss 2 or 3. It's just how it goes, sometimes. My advice. Warm packs, if the patient is mobile enough, have them hang the arm off the edge of the bed, low, for a few minutes, this allows blood to pool to the extremity thus "puffing" up the veins. Tourniquette a couple fist squeezes, if they can. Look and feel, don't feel with a glove because you wont feel anything. A big one, I tell all my students, don't stick them if you don't feel or see anything, that would just be silly. Constantly mess with your own hands and arms, not actually sticking, but feel where your veins are, see what makes them puff out and what makes them hide, chances are your patients will be similar if not the same. Also, chances are where you have a big vein, your patient will have one in that GENERAL area too. Lastly, if you don't see or feel anything, there is no shame in calling the vascular access specialists, if you have them, and having them use the ultrasound machine to find a nice deep big vein.
As far as the poke, find your spot, try not to go anywhere it is bifurcating or if you are so blessed to be able to feel valves, obviously avoid those. Stabilize the vein, hold a finger or a mental spot of exactly where that sucker is if it isn't visible. Another good trick keep the corner of your skin cleansing pad right at the point you want to insert, this way you won't lose your spot. Have everything prepared, stabilize the site with one hand, and insert the needle at a moderate angle, the angle depends on how superficial the vein is, and this I can't really describe in words, you kind of just get a feel for it. If there is no flash back right away feel free to maybe advance a very little bit, or pull back a very little bit and slightly reposition and re-advance, be patient, do this until you get blood. Don't give up after the first 30 seconds. Sometimes it takes some finesse and a whole lot of praying . Don't give up, keep practicing. The only way to get good at them is to do them, and try.