This is good advice.
Record your rehearsals and Shows.
This is great advice because it really does provide perspective. This is especially true for singers because they hear themselves 'in their heads' literally and there is often a real disconnect between how they think they sound...and how they really sound. Remember how weird your voice sounded to you the first time you talked into a mic?
Most bands really do suck...they just do. However, everybody in pretty much every band in the known universe believes that their band is good. It's a weird paradox like how people give congress as a whole low ratings, but their own congress people high marks. So, how do you know then? The best indicator is a following...a real following made up mostly of people who ARE NOT YOUR FRIENDS OR FAMILY. Are there great bands that are unable to build a following over time? Rarely. Are there really sucky bands that are able to build a following over time? Rarely as well. (Insert Creed and Nickelback jokes here). There are always exceptions, but this is the best gauge there is.
Throw Events.
Yes, Yes, and Yes! I played in many successful original bands before my now illustrious career as a Cover Band owner. We utilized this concept and got great results! We used to do 1 show every 4-6 weeks in my most successful band. Here is what we did from the beginning. When we started, we would only play a venue we could PACK. If people got turned away because it was sold out... It just added to the mystique..and besides...people ALWAYS want what they can't have. Only when we were selling a venue out comfortably would we move into a larger venue...but we would always make sure that we picked the right room to provide the perception that the place was packed. At our peak, we would draw 800+ consistently at $7-$10 a head. Now I get the allure of picking band names out of a hat...and it sounds like it works...however...we employed a different strategy. We only booked top drawing bands who put on killer performances, and added a musically cohesive vibe to the event to OPEN FOR US. We only booked bands who's followings would dig all the other bands on the bill too. We didn't headline because we were arrogant (although, it is a benefit to the way people perceive your band to sit atop the bill) but rather because we had the biggest following. It is beneficial to the event because our fans would come early to get in before it sold out, watch all the other bands, and, it would still be totally packed at the end. There is 1 major issue I see with drawing out of the hat; say on a 4 band Event, 2 of the bands have huge followings, and 2 have average followings. Let's say the 2 with huge following go on first and second....how many people will be left in the venue for bands 3 and 4? This is why festivals always put the top draws at the end of the shows too! Oh....and did I mention that we used to canvas entire areas with posters, drop little fliers at every record store in town, hit campuses, etc... If we were throwing an event, and you liked live music, and were in your 20's, there was no way you didn't know when we were playing. We also bought ad space in local rags to promote our shows.
My 2 cents.