I bought a 3/4 Singer in the late 80's. It's been very, very good to me. Know nothing about their quality now, so can't recommend. My friend got a $$$Juki and has had nothing but heartache.
Get lessons. I work in a fabric store and see too many people buy one and then just let it sit because they're intimidated.
Some sergers are easier to thread than others. Try them out - don't just let them pull the threads through at the store to show you how simple it can be - do the threading yourself and you'll know if you should consider the machine or not.
Before buying, read buyers' reviews online.
Hope you find one to love. I always say my serger changed my life. Really, I do!