Research is a great skill but I would still go with basic charming or tough interviewing skills first. interviewing skills will help with multiple people. Research will only eliminate 1 suspect.
each person has their own way of solving cases and getting skills. but someone else said it this way, why go through all the trouble of accumulating 13 pts when you can pick up a skill at 6pts that will help you now? true the more experience you have the slower it gets to earn pts. but if you have more skills, then you can do harder cases to help offset that.
I am with giulianar on this. Research is good, but it won't do enough for you when you can't complete your suspect list, for example.
So my vote is, if you are tough, get Interrogation and Intimidation - all levels - as soon as you can.
If you are charming, get Sweet Talking and Rule Bending - all levels - as soon as you can.
Sweet Talking/Interrogation work with suspects.
Rule Bending/Intimidation work with townspeople.