Rim strips are a must, otherwise, your spokes will pop your tubes, I like Velox from France, but you can use electrical tape if you're on a VERY tight budget.
I like tire liners - Mr. Tuffy being my personal favorite, but there are many other options - they don't stop nails (or caltrops, but we]re not quite at that level just yet....), but do help if there's a lot of broken glass or (young) got heads in your area. Mature goat heads can be like nails.
With liners AND Slime, you're about as safe from punctures as you can be, but be aware that Slime and patch glue do not get along, so you kinda need to pick one or the other.