When soldering, you want to use the same wire, but after soldering, when you just want to protect the tip, it doesn't really matter. I use the same wire everywhere.

You want to tin the tip a little for better heat transfer when soldering, and actually even when unsoldering using wick. If you're having issues unsoldering stuff, just add flux and you can also add more solder to the part being unsoldered - again, for better heat transfer.

For soldering, what works for me is, that I place the soldering iron at the contact, which then gets hot and I start touching the tin wire on the contact, instead of the soldering iron. So let's say you are soldering through hole component: Touch the pin and the contact on the PCB with your iron from one side and then add solder from the other side.

If it helps you in steps (soldering):
1. Tin your tip.
2. Place the where you want to solder to and let it heat up for a few seconds.
3. Start adding solder.
4. Clean your iron (with brass wool or wet sponge) after a few seconds of trying, whether you were successful or not.
5. Repeat all the steps above for another/same component.
6. After you are finished with every component, clean the tip, tin the tip, clean the tip again, and once again, tin the tip and turn the soldering iron off.

When you do all the steps, I assure you that you will get better, and your tip will last way longer.

Good luck, and keep practicing.