Having been absolutely atrocious at IV access, I believe I am qualified to speak on this topic:
The first thing you need to do is prepare mentally. Even down to what you say to your patient. Instead of saying "I'm going to try and give you an IV" say "I'm going to give you an IV". If you go into it saying "I'm going to miss this IV", you are.
When you're preparing to start an IV, place the tourniquet on the patient's arm. After that, prepare the rest of your equipment. This will allow plenty of time for the veins to "plump up". The first thing I do is look for veins. If you look and can't find one, try feeling. Remember, some veins will appear as nothing but faint blue shadows.
Some tricks of the trade...
Close your eyes when you feel for the veins. This will prevent your eyes from playing tricks on you. If you find nothing, trying placing another tourniquet. Place it on top of the first or place them "one above, one below". There is also a device called Veinlite EMS to aid in finding veins, which I will provide a link for at the end of my post. I had a patient last weekend with a possible MI who said "Good luck getting an IV on ME"... using double tourniquets I got bilateral 18s. The doctor at the ER was very pleased lol
When you perform the venipuncture, hold the catheter in a way that's comfortable for you. When I started, I held the catheter between my thumb and middle finger using my ring and pinky fingers for stabilization. That was ineffective because I was using my two weakest fingers for support, which didn't allow me the stability I needed, especially for difficult to access veins. Today, I lay the catheter between the second and third knuckle along all four fingers and advanced the catheter with my thumb, sliding the needle and chamber back by moving my fingers back. Unorthodox, but it works best for me. Take a catheter and hold it a few different ways, see what works best for you.
Go in at a low angle. This lowers the likelihood of you going into the vein and out the other side. Hold tight traction, but not too much. Not enough, the vein rolls. Too much, you flatten out the vein. Go in until you see the flash, slide the catheter in just a little more, anchor down right against the skin, advance the catheter and slide the needle out.
There are countless other techniques to try, but in the end there will be times when you just won't be able to get an IV. If your patient is critical, there are alternatives to peripheral IV access.... EJs, IOs, etc.
Remember, you JUST started. It's going to take time for you to become proficient.
Hope this helped...
Veinlite EMS:
http://www.veinlite.com/pics/Veinlite EMS Flyer e-mail.jpg