Some procedures to improve 1st layer I'm wondering if anyone can confirm this improves the success rate of the first layer by doing this before starting print.  My case is using ABS with a Reprap.  In may work on other 3D printers and materials.

Heat up the bed and extruder to the starting temperature long enough to stabilize, so that the printer sets a more accurate z-height at the start.  While your printer may wait until temperatures are reached, it will usually start immediately without waiting.

After the extruder reaches starting temperature, wait until the filament material stops extruding from the extruder. Remove extruded material.  This reduces failures due to material extruding before the print, but after the start, ending up in the wrong place.
You don't get a more accurate Z height when you heat the printer and let it settle. You get a different value that will work perfectly. E.g. I've got printers that do bed leveling cold but print with the correct initial Z height to get a perfect first layer. This is also valid for manually trammed beds. The only settling you might need if for thick glass beds so that the heat can be spread evenly, but operating thick glass beds I've never had to settle the bed, just heat up and start. But since ABS is prone to shrink, heating the bed first and then the hotend might prove valuable, at the time the hotend reaches it's temperature, the bed had time to evenly distribute the heat.

Oozing isn't good, maybe retracting filament at the end of a print might stop oozing for the next print. Most higher end printers therefore have a purge/prime, wipe and retract procedure prior to printing.