I think the biggest thing to know about starting a weld with a stick rod is that the goal is no never really strike the rod onto steel. It is arc welding, so you are trying to establish an arc as soon as possible. It is no different than a spark plug, you need a GAP.
I typically scratch start...like a match, but I can tap it too.
With 7018 rod, the flux will coat the rod after a weld is made. That is why it is harder to start a weld with a previously used 7018 rod. BUT here are three tips to help with that.
1. If you are welding alone, immediately after making the weld, "flick" the rod hard. The ball of slag will fly off the rod and you can start the rod again easier. (A welder got into the habit of doing this, and I was fitting pipe for him, and I was constantly getting burned. Only do this while welding alone!")
2. AFTER the rod is cooled, take your thumb and break off the little nib of flux that forms over the rod end.
3. Take a piece of lumber...wood...and while the rod is still hot, bury it in the wood. It will keep the slag from forming over the rod.
Try any of these three tips and you will readily see what I mean. I prefer the wood block method because it does not cause burns or fire danger like #1, and it does not cause the tip of your glove to burn out).