HOW TO DETERMINE WHICH MUTUAL OR INDEX FUNDS ARE BEST TO INVEST IN?

Hi,
I am brand new to this area of financial as well as have no believe or backround preparation in it. I longed for to know how to establish that supports have been the most appropriate to deposit in. I have review the little element online (limited myselfto tip behaving funds) though still feel exposed given I do not feel I have believe whatsoever to feel assured that the sold account is what will be befitting for me. Are there any indicators that a single should demeanour whilst chooosing mutual funds?