Here's my two cents as I work on building my climbing skills with the V20:
1. Spin rather than mash is good advice. But the trick is to find a good spinning cadence for this bike. I'm finding that a touch of resistance really helps with the balance. I trained myself years ago to spin at 90-100 rpm. This doesn't quite work for me on hills with the V20. If I slow it down to 80-85 rpm and get just a bit more bite in the gears, I'm better able to maintain both my line and my heartrate. (I'm running round chain rings and standard length cranks. I spin them just fine on the V20.)
2. ratz's advice about downshifting early is great. I'd add the following caveat, plan for the hill to be longer than you expect. Better to conserve your energy than power over a crest. Each power move in climbing will sap a bit of your reserves for the whole day. Parcel those out parsimoniously. This also helps when you hit a false flat. There are times when you will need power like at a stoplight crossing a busy street. Don't spend it foolishly.
3. ratz gave me a piece of advice in another thread that resonates. You can probably walk your bike at 3.5 mph uphill. If you hit a steep section and you're killing yourself to creep along, swallow your pride and walk.
4. The CB geometry requires some upper body relaxation to ride well. If you 'pop', your heartrate and upper body exhaustion will make it difficult to ride straight. Keeping your heart rate in check is a good gauge of your climbing technique for a given hill.
5. Don't expend energy on the descents and bottom of climbs when you don't have to. These bikes coast very well. I find that if I let her coast, Sigr-D flies casually alongside of DFs who are pedaling on descents. Coast as far as you can up the next hill until you can begin getting bite at a good cadence in an appropriate gear.
5. Learn what gear to start a climb in from both a standstill and a coast. Over spinning too small a gear or getting trapped in too large a gear at the bottom of a climb both sap your reserves.
6. Not all roads are good for newby Cruzbike climbers. Narrow shoulders on a busy road is a recipe for fear and exhaustion. The combination of worry, increasing instability and building exhaustion compound in these scenarios. Walk if the conditions warrant walking and if you are becoming a hazard to the other riders. I've found this is necessary in some event rides.
7. Learn to gauge your spacing. Sigr-D is the best bent I've ever ridden among DFs. But she is not a DF. There is a rhythm to riding her effectively among DFs. My goal isn't to leave the DFs in the dust. My goal is to learn to ride with them. I find I need to leave the right gaps going into and out of climbs.
8. Judge the type of hill. Long steady grade or varying pitch? Downshift before pitch changes.
9. Finally, climbing is a mental game. Sing, go to your happy place, shorten your focus to ten feet ahead of you or anything else that can help you get your head in a positive space. Attitude really matters. Fake it until your fitness improves. Tell yourself that you've got this. Truth is that you do.
I walked up a steep slope in an event ride last month. At the top, a DF rider congratulated me. I told her I walked most of the climb. She looked at me and said, "You got up that hill under your own power. Who cares whether you did it pedaling or walking? You conquered that hill. Have fun on the ride down. You've earned it."