Whenever possible, try to avoid pouring or letting any NaOH solution out of its container. Instead, rearrange the steps so that you dissolve the NaOH in the final container, then add your MHRB soup to that container.
So, instead of something like this procedure:
1. Add water to jar, then add NaOH, mix.
2. Add NaOH solution to MHRB soup.
Instead do this:
1. Add water to jar, then add NaOH, mix.
2. Add MHRB soup to jar with NaOH solution (slowly!)
This way you minimize the chance of spills. In addition, it is important to add the NaOH to water, rather than the other way around. Not following this can result in a greater chance of splashes or spills. The procedure I'm fond of doesn't require pouring any NaOH solution at any time, except for disposal.
Finally, it's best to use the lowest concentration of NaOH you can manage - a lot of teks seem to call for you to add wayyyy too much or to form a saturated solution. Not only is this wasteful but also makes things way more dangerous than they have to be. I've always stuck with just enough to get to pH 12-13, so around 30-40g of NaOH per liter of solution, works great.
As an aside, don't do anything idiotic like I did - I was once trying to break up an emulsion that formed between basified MHRB soup and naphtha, so I put my reaction jar on top of the washing machine, started it, and walked away. 5 minutes later I hear a sickening crash from the other side of the house - the jar had migrated off the edge of the washer and fell onto the concrete floor and there was 1 L of black base soup all over the place (even on the walls). It took several hours to clean it up thoroughly - had to soak up as much as possible with paper towels (placed immediately in a special garbage bag), then washed the floor with vinegar multiple times. Gloves were essential.