Pricing a home is more art than science. The 'right amount' is in the eyes of the beholder, but here are a few suggestions:
Have your agent run the recent comparable sales directly around the home: that should give you a good idea if your offer is in the ballpark.
What adjustments up and down did you make when you came up with your offer? They should include adding or subtracting value for features such as location, views, and condition.
What did your agent say are the possibilities that there will be multiple offers?
Another thing to consider is how much the home is worth to you; how does the home make you feel? That may sound silly but if it is 'special' you know it and you will want to give a strong offer up front- there is nothing worse than to loose out on something you really want by an amount that you would have been willing to pay.
Unless you are offering cash & you don't have an appraisal contingency, once the offer is accepted by the seller, an appraiser for the bank will give their opinion on value. Because of the current credit climate, many appraisals are coming in low (especially on FHA or similar loans where the buyer has a down payment less than 20%).
So don't be afraid of offering too much because your lender will not lend more than what they think it is worth.
If your appraisal doesn't come in at your offered price, the options are:
Is the seller willing to renegotiate the price?
If not, can you & will you pay the difference or maybe split it with the seller?
If not, are you willing to walk away?
Best of luck,