Split ends definitely need to be gotten rid of! This is why everyone says that trims encourage growth. Split ends and overdead hair can start ruining the hair shaft above it.
Definitely avoid heat like everyone says. Before I ever started dying and straightening my hair years and years ago, I NEVER got split ends. I think pulling my hair into a ponytail all the time helped as well, as hair that lies flat on your body can get tangled in things much easier, or even tangled amongst itself (this of course is advice for when your hair reaches those lengths). Just whatever you do, avoid causing further damage!
I'm actually in need of a trim myself, but I'm avoiding it at all costs (it took so long to reach this full SL!) I don't think I have split ends, but my ends are incredibly damaged and dried-out. But to lengthen the time between trims, I make sure I use damage repair shampoos, conditioners and deep conditioners. I use a leave-in conditioner (my new favourite is Profectiv Beautiful Lengths hair lotion, it helps strengthen the hair and prevent further breakage and splitting). And if I NEED to straighten, I make sure to use a heat protecting spray. This is a MUST! So far, I've been able to "heal" my hair a good bit this way. I may be able to get away without trimming until after summer if I can keep up with everything (now that I'm keeping away from heat and bleach/hair dye).
Also, the right hair brush can help prevent split ends! Mine looks like this, and I love how it glides through my hair and never gets caught (even when my hair is wet):