to start with, install the offset trim recommended in the data sheet. second, whatever you use for an input resistor, use one of equal value on the opposite input (this is essential with a 741 which has high input bias currents) this also should be covered in the data sheet. if it isn't, read application note AN-A from National Semiconductor, which will explain it in detail with examples for both inverting and noninverting circuits. to mitigate the gain error, use 1% tolerance resistors, or use added low value series or very high value parallel resistors to trim your feedback resistor. it would help me be more specific as to what you can do to eliminate the errors if i knew what you are trying to accomplish. a schematic would help.
you will find on this forum that vague questions don't often get very good answers. that's because answering vague questions require a "shotgun" approach. all we really know so far is that you're trying to measure or level shift a voltage with a voltage range outside of the abilities of most op amps with a level of precision and/or accuracy that isn't commonly required, and with no clue what you're trying to accomplish as an end result.