The best thing I can recommend-- and there are definitely journeys here that are best/easiest done by bus, just as there are journeys that are best/easiest done by metro or on foot -- is a map BOOK that I still carry with me every day even though I've lived here nearly 10 years. It's called Paris 3 Plans by Arrondissement and is published by l'Indispensable, has a blue cover. You can buy it here and there, but always in the book section /Paris travel section of the BHV store at the Hotel de Ville metro stop.
As the name suggests, it has three separate maps (two-page spread) for each arrondissement:
-- one shows the streets in detail
-- one shows the same but with an overlay of the metro lines
-- and the third shows the overlay of the bus routes on the streets.
This is the book that makes the bus system usable and easy for me. The other books that show the lines only don't help me too much because the lines are out of context. But with this map, I can look at an area and see what bus lines makes the journey that I want to make - then I find out its name/color and where its stops are. And of course you can "put together" a trip across arrondissements by referring back and forth (there's also a Paris-wide bus map in the back of the book to give the big picture.
Sometimes the bus is crowded, and sometimes it's not. Sometimes you're cruising along and it's taking you much more directly on a route that would take you three lines/two changes on the metro. Sometimes it will get you somewhere the metro doesn't go conveniently, and sometimes it will be stuck in traffic (guess what, sometimes the metros get stuck too, as was my experience last night on my way home on the Line 1 from work). But sometimes it's pretty funny to ride the bus around the Etoile at the base of the Arc de Triomphe and be a part of the swirling cacophony of traffic coming in from the 12 different streets that feed into it -- while someone else is doing the driving.
The buses are also a lot more user-friendly now that they have installed all the new bus stops which almost all have the electronic board showing the time until the next bus (it makes a difference often as to whether I want to wait 3 minutes until the next bus or know that I do NOT want to wait 18 minutes for the next one). Also the signs marking the bus stops are much taller and more visible from further away, helping a bit with Dick's issue of finding the stop in the first place. They're simply better sign posted now.
So you see, I'm a big fan of the buses. Would I advocate always riding the bus? No. Do they have their place and are they incredibly useful? Yes. But you need a little help figuring out when/how they will be useful, and the best way I've found for that is the 3 plans map.