There is really no answer for this, it varies by traffic source, niche, targeting, offer, etc. what I worry about more is the epc (earnings per click)

What's a good conversion rate for CPA campaigns?
Like Chris said there is no exact answer to this question. Too many variables.

Also whats an easy yet effective tracking software to use? Your favorite?
Check out CPVLabs.

A good conversion rate is any rate where you will earn more than $1 for each $1 you spend acquiring traffic. Given only your commission and your cost per click, you can calculate what that minimum profitable conversion rate is.

Conversion Rate = 1 / (Commission / Cost Per Click)

Example: $25 commission, $0.25 per click: 1 / (25 / .25) = 1%

Example: $25 commission, $1 per click: 1 / (25 / 1) = 4%

Example: $50 commission, $1.50 per click: 1 / (50 / 1.5) = 3%

Once you've established what your conversion rate is for a given product, market and set of ad creatives, you can use that data to calculate the maximum cost per click you can spend on new placements the same way.

A Max. CPA bid is the most you're willing to pay for each conversion, such as a purchase or signup. When you use Conversion Optimizer, most of your bids will be below whatever maximum you set.