Hey I just don't sugar coat my responses, but I've been taking the time to try and help so bite me if you don't have a sense of humor
The reason to use the oral syringe is simply because its bigger it's easier to handle and work with. Also, using a standard syringe with the needle pulled out will work, but it wont hold much liquid and even with no needle those things are so skinny they are kinda sharp on their own, so it's possible to hurt yourself.
I've used the oral "child syringe" for years with excellent results, and I think most pluggers prefer it. Just do a thread title search with the word plugging and/or put my name in the "search by author" part of the advanced search menu and you'll find all MY posts about plugging and I have posted all you need to know.
Also, when you decide to try IV again, don't just go by sight alone - learn to feel the vein under your skin. Touch it with your index finger, do a gentle "bounce bounce bounce" with your index finger over a spot where you know a vein is and you WILL be able to feel the slightly spoungy texture. Once you got the hang of it, you can use your sense of touch to hunt down the exact location of other veins, using the "vein map" image at the top of this thread and elsewhere.
Like ive mentioned before, I can't see ANY of my veins and have learned to find them the Helen Keller way. How much of an angle you go in with the needle depends how far under then skin the vein is; if you can feel it right under the skin, then a shallow angle of like 20 or 30 degrees is good; if you think the vein is further down, sometimes I go in at a 70 degree angle (this is where the "draw back first, then push" technique makes all the difference).
Someone above suggested 27 or 28g needles but I wouldn't recommend it unless you are 500 pounds and have leather skin, those needles are way too thick. 29-31g is a better range, I think. You want to use the thinnest needle that you can, since it will pierce the skin more easily AND leave behind fainter marks.
Honestly, you've gotten two pages of very good advice and an entire IV megathread full of advice. If you're still asking questions and freaking out and looking to be talked through the process by Doctor Bob then maybe you're just not cut out for IV drug use. There's nothing wrong with that, in fact EVERYONE is better off without it, so you'd be lucky if you just gave up on it.
Try plugging, make sure you follow instructions and do it right, its guaranteed to make you feel good, just don't expect an intense rush (personally, I'd trade the rush for two hours of feeling warm and fuzzy any day of the week).
Good luck and may the FORCE be with you.