I've been messing around lately trying to figure out the usefulness of hand held radios. Realistically without a repeater expect 0.5-1.0miles in typical terrain (houses, trees, mountains). Unless you have completely unobstructed view and no interference (mountain top to mountain top, over water, etc) , you aren't going to get multiple mile range.
Using a repeater, you can probably go up to 25 miles. This really depends on where the repeater is located and if your radio can reach it. Because repeaters are usually on top of mountains with large antennas and lots of power, you can usually be able to hear them. To be able to have 2 way communication with someone your radio needs to be able to reach the repeater. Because they are up higher with larger antenna's it is easier for your radio to reach them at greater distances.
For example, you may not be able to reach someone 2 miles away in simplex mode (same channel, direct communication, no repeater), but could talk to them if you use a repeater 10 miles away.
The challenge is find repeaters in your area that you and the party you want to communicate with can reach and use.
There are many sites that list repeaters: (note that unless you have a digital radio, you cannot use digital repeaters, so just look for FM repeaters.
MyGMRS.com (requires payment to get the tone info, but you can use a scanner to find them. see below)
RepeaterBook.com - NJ
RadioReference.com - NJ
ARRL.org (uses RFinder.net) - requires subscription
I found the RepeaterBook phone app to actually work well.
Unfortunately I've found that they are woefully not up to date. Many either aren't working, aren't used, or even though they should be in range, apparently I am not. Also I have found (by using a scanner) that there are many that aren't even listed.
The best way I've found to see what is actually in range is to use a good scanner (a real one, not the scanning feature of your Baofeng). You will need one that can detect CTSS/DCS tones. Repeaters use these codes to open up the channel and rebroadcast your input. Without these codes, even if you transmit on their input frequencies they will not repeat. Basically in order to use a repeater, you need to know their transmit (TX) frequency, receive frequency (RX, usually listed as either a + or - offset from the the repeaters transmit frequency), and their RX CTSS Tone or DCS Code. Some repeaters do not use tones or codes and so their tone/code will be listed as CSQ.
Once you find the repeaters and their receive offset and tones, you can program them in your radio with the CHIRP (or similar) software.