Please note, I am not an authority, these are just my own ideas.
Some people have a tradition to only use white - white on white for tzitzit. The mitzvah is to ideally attach it to a beged - i.e. a garment - which I think should be something one likes to wear. So it has to retain its value as a beged and not as an "under-beged". I think we can try to beautify this mitzvah by using a fabric that you are likely to wear within the halachic parameters. They can be natural fibers like wool or cotton (wool is ideal but cotton is also permitted) but not synthetic fibers, i.e. polyester, nylon, mesh. BUYER BEWARE: some tzitzit garments are currently on sale not only online, ebay etc. but also in stores that may not be k'halacha!! One has to be aware of these issues. Wearing them on Shabbat may be considered carrying. Always check with your local orthodox rabbi if there is a doubt. I will hopefully post my sources on this soon.
Sleeves may be another issue.
Right now we are looking into possibilities for collars and beautifying them as well as different material designs.
Then there are the tzitzit strings themselves. If you google tzitzit or search on ebay, you will find items for sale that call themselves "tzitzit" under various marketing terms that are pre-tied corners of tzitzit in different colors and patterns as well as fibers!! These are definitely not kosher. They are designed to be attached to the corner of a garment or belt buckle via a clasp! There is NO MITZVAH to use these whatsoever. If you go and search on ebay they have people quoting Christian sources and inventing string formations and selling them. I'm not kidding (wish I was!) - go check for yourself!
The strings have to be made leshem mitzvat tzitzit. And they have to be knotted onto the beged and thus part of the garment and cannot be removed. Halachically it takes at least 2 knots to be considered attached to the beged. Strings should only be bought from a competent seller with kosher certification. It has a seal. Normally there are 2 qualities available - kosher, machine-made tzitzit as well as the hand-made variety, which some authorities prefer.
Happy Tzitzit Wearing!