OK so first off thanks to this board I've managed to get my hair well past shoulder length. It's been a 3-year project with many trims along the way.
I've been wearing it loose but per the discussion below, I do have to look professional occasionally and I'm trying to figure out how. A ponytail looks a little odd, it has a lot of volume and wave. So I've tried a 2nd tie tonight but the result was also odd, the middle section bowed outwards and looked "sa ggy". Is there any trick to getting the ponytail looking nice with a 2nd tie at the bottom?
And a follow-up question: is there any trick to getting a bun to look good? I think that would be the best look for me for work. Maybe the best approach is to have the ends stick out kind of messy, rather than wrapped up too neat and tightly?
I'm just using hair ties found at Walgreens or whatever, let me know if I have the right tool for the job. I am unwilling to go the silver buckle/leather strap route (I don't wear a bolo tie!)
The best hair ties are the kind without any metal bits on them. So long as yours haven't got those, you should be fine (and of course, never use regular rubber bands).
Here are some instructions for making one kind of bun: http://gollan.pwaresearch.com/hp/bbbun.html
Just be sure your hair is wet (not drenched, but still damp); it's next to impossible to get it looking right with dry hair.

Tying a segmented ponytail is not difficult. Putting ties close together will stop the saggy look. With wavy hair of your length, you will need more than 2 of them. You will likely need 5 or so.
Put your usual top tie in place, then put the second tie about 1 inch below the top tie. With your hair BEHIND your back, slide that second tie down 2 inches, leaving a 3 inch space between the ties. Now your hair is secure. For the third tie and beyond, bring your hair to the front so you can see what your doing.
For straight hair the intervals can be as much as 5 inches. Depending on how much wave you have, you may want to use 2 1/2 inch intervals between ties. Multiple ties will straighten your hair out a bit and make it look very neat and well kept. Multiple ties will also greatly reduce tangling.
For 3 inch intervals:
#1 top
#2 at 3 inches
#3 at 6 inches
#4 at 9 inches
A photo of your hair (from the back) would be helpful. This would allow me to give you the best possible advice.
Absalom