Based on recent experiences:

1.  Give yourself enough time.
Usually, companies replace/upgrade their ERP/Accounting systems only when they have to –  and the subsequent implementation date is then usually, yesterday.

In my opinion, you need at least three months to evaluate your options.   Make time, it is a big, expensive – and painfull – change.

2.  Know what you want.
Yes, sounds obvious, but it is very easy to be distracted by new bells, whistles and possibilities.  Make sure your core requirements (“pain points”) are fulfilled first – then look at the niceties.  Also, a fixed set of criteria simplifies comparisons (‘apples with apples’).

Customization/expandability in software systems is always an important criteria.

3.  Let the users help decide.
Get your key system users involved right from the start:  thoroughly sell  the reason for the upgrade/replacement, have them attend function specific demos and draw up a ‘User experience’ comparison afterwards.  Not only does this take the pressure off the (usually) sole decision maker – it also improves change management dramatically.

4.  Have a demo – and a database – installed.
If you’re a hands-on system admin (like myself) – you’ll be able to learn a lot from – and evaluate/compare very quickly – a new system, just by looking at its database structure.  First prize would be to have a working demo front-end as well, push for this!  Then test your core requirements – or have the vendor demo it for you (and your key users).

5.  Make a few calls.
A quick and cost effective method to obtain an industry opinion of your options.  What does your customers use?  Is there enought support around?

Let me know if you need help!