Leading Aces in the game of Spades
It depends on a lot of context whether leading an Ace is a good idea.  

When to lead an Ace:

Leading an ace when you have strong control of the suit is good.  For example, leading from A-K or a bare Ace is good.  Since you can win any follow up, you don't really lose much if your opponents playing low.  And it can also give your partner an idea of the strength you have in that suit.  

You also may consider leading an Ace when your partner has bid nil.  This gives your partner an opportunity to get rid of problematic cards in that suit.  

If you think your team underbid, you may also want to lead the Ace to actively weaken your hand to avoid getting too many bags.

When to lead another suit:

Leading an ace is not usually a good idea in the early part of the hand when other players are unlikely to be void in suits.  Assuming you don't also have the king, your opponents are twice as likely to have the newly promoted winner instead of your partner.  

You can still play the Ace the first time the suit is lead if you're paranoid about the risks of voids, but you'll get extra value from your opponents playing ahead of you.  And you might even be able to win an extra trick due just to your positioning.  

If your suit is long but weak like A-T-x-x-x-x-x you probably want to hold suit control instead of leading the Ace.  It's too risky to lead this Ace and then have your opponents get valuable discards while also winning tricks.  

Additionally, if you can get trump control, you can run these lengthy side suits, so saving the ace to win important tricks can be very helpful.  Leading the suit outright negates this advantage.  

Do not underlead your Ace:

There is almost no reason to underlead an Ace.  You put your Ace at risk of being trumped while also giving up the positional advantage to your opponents.