I need to pull 3#10's stranded thru 50' of 1/2 emt. I have another run of 4 #12 solids also in 1/2" emt.

I never pulled wire before, don't have anyone to help me. Need some tips. Is this a bad idea to do by myself?

 

Strip 4'' off of all but one of your wires, then strip the last one 7 or 8''. Twist them together as if you are making a joint, leaving the excess 3 or 4'' on the long one sticking out. Take the excess and loop it through your fish tape/twine/ whatever you are pulling with. Squish the loop down with pliers then tape it all up.
Or if your run doesn't have many bends you may be able to get away with just pushing the wire through.
Having a 2nd person helps when pulling so they can feed the wire for you, thus reducing the chance of scarring it.
If you are working alone, there is a neat little tool you can use to help reduce scarring.
Rack-A-Tiers - Specialty Electrical Tools | PulLee

 

Here's another handy little gadget to pull wire by yourself without scuffing or damaging the insulation.

Madison Electric Products :: Electrical Product Inventory

 

The solid #12 should push in by hand if you tape the ends together and don't have too many bends.

 

I was able to push the #12's no problem, it was a breeze.

I am tempted to try the same with the #10 stranded... do you think I can push those?

 

I think you'll have to pull the stranded conductors, but you can give it a try.

 

In 1/2" pipe? Maybe, if it's a straight pipe no more than 10' long and you make a good pushing head -- a tight loop -- on the wires.

 

Joe,
I want one of those, looks neat!

 

Yea, they are pretty cool and will fit just about any kind of box you can think of.

 

This is why we always use solid wire. You can push it in without using a tape in most cases. stranded wire is like pushing a slinky in a box.