Well theres a few things you can do to help yourself out mate, Ill let u in on the secret.
1) Before soldering, use a ruber (eraser) to lightly clean the copper.
2) Tin your iron before every joint, all you have to do is put a bit of solder on your iron and then clean it off, this aids heat transfere
3) To have immaculate joints, buy ureself some flux. Flux aids heat transfere and the solder will flow around the joint, instead of being a blob of sticky mess. Just apply a generous amount of flux to the joint and solder away
4) wait till it cools and then clean it with a paintbrush (stiff bristles) in IPA.
If you do this, after a bit of practice your joints will look profesional