Investors get into the tax sale arena for two reasons:
1) Getting a guaranteed great return on their money
2) Possibly getting a deed to the property for really really cheap.

Now while these benefits are definitely attractive, you still have to keep in mind what you're getting into.

Are you buying a certificate that is redeemable by the owner or a deed itself?

If you're not getting a deed, are you willing to wait out the redemeption period where you really can't improve the home since you don't know if it will truly be yours or not.

So education is of prime importance in this business.
You really want to know what you're getting into.

In many municipalities, tax lien investing can be done completely online.

This has good points due to convenience, but you still have to do research on the property. You don't want to pick up some HAZ Mat piece of land that is of no profit to you at all.

In many cases, you actually have to bid on the interest rate paid on these liens. While the bidding might start up pretty high, you may also find yourself bidding the interest rate down to 7-8%. YSome positives are that you can invest in tax certificates and deeds from the comfort of your own home.

You can invest tax free by using a self directed IRA (More info here)

And there are ways to get tax deeds and tax liens that have very little competition.

One of the best things you can do, although many tax lien/certificate investors do not do is to deal with the homeowner themselves. This gets you into a great position way ahead of the competition.

An example of this is buying their redemption rights to the property. Pretty nice move!