It sounds like you got the job started right! Pre-tinning the wire is a surer way of making sure you have a good joint. When you go to join them sense you have pre-tinned them you will not need much solder on you tip and with 70W you should only nedd to touch it and you should see the solder wick into the space between them. If you tape one wire down at the edge of your table and then hold the solder iron in one and the other wire in the other hand then things will not more around so much!