Honestly I am of the opinion that new affiliates should learn the basics before they invest.
The best investment as far as I am concerned is in S builder. This will give them new affiliates using them a team can be built.
Secondly a standing order for 1500 points to maintain EA status every month is an attractive investment.
New affiliates can also invest in e books regarding internet marketing.
These are the three prime investments for a beginner.