Re: Irimi Nage
For me, the iriminage variation I end up with often depends on what uke is doing. Ive been lucky enough to train with a handful of aikido organizations and steal any tips, tricks, or full-on techniques that work for me. Iriminage is no exception - so you'll often see me doing about three or four very different looking kihon. Some things that are important to me are;
actually off-balancing uke from the beginning, while getting control of his or her center. I do this by ensuring whatever I am holding onto (collar, neck, etc) is snugly attached to some part of my body (generally chest or far shoulder, whatever so long as I can get my non-holding arm around for the throwy part).
I also ensure uke's head is misaligned from his spine, off to a side or corner. I try not to ever let uke have their head in the same line as their hips/spine as they can regain balance with little effort.
I don't bring uke to the ground. I don't like to be in a situation where I have to fight them back up, I feel like it's too time consuming, and also the reason mentioned in the above paragraph.
Other than that I just make sure I am throwing with my body - as in my chest/armpit area, and that uke is completely under me and not floating away.