What I learned from painting my '79 Bronco with Monstaliner. Monstaliner provides good instructions with plenty of detail, but there are few things they don't describe too well.
-It's a great value. It does seem pricey compared to other bedliners, but for the quality and easy of installation it was worth it. I had about $350 into the paint (2 gallon kit plus 3 colors since one of the colors I used was a mix of two) from Monstaliner plus random other supplies like rags, acetone, etc.
-Give yourself plenty of time for prep. If your paint is old and crusty like mine, you don't need to do much sanding. You just have to get rid of the gloss and any flaking spots. There are some sanding pads that come with the kit. Also, make sure you take care of serious rust- Chassis Saver is a good option. You can use this link for a promotion for free Chassis Saver and shipping. They honored it when I ordered this summer (2016). I used gloss black Chassis Saver since I'm also going to use it to paint my frame, but if you're just using it on the body I would use one of the other lighter colors so it's easier to paint over (fewer coats needed).
-Order lots of extra rollers. If you're really set on having more pronounced texture, you probably need at least four, probably 5, per gallon. The 2 gallon kit only comes with 3 in all. Don't use much pressure when rolling, just enough to get the paint to come out of the roller. Keep the roller full of paint, roll VERY slowly, and don't push too hard. I learned the hard way that the roller will disintegrate very quickly if you push too hard and go too fast, leaving you with lots of little blue flecks in the paint and chunks that stick up. I used regular paint rollers for the first coat (or two for spots where I was using a very different color from the original), then used the provided foam rollers for the final texture layer. I think it turned out a little less textured that it would have otherwise, but it was worth it not to have the little pieces buried in the paint.
-2 Gallons worked out really well for me for the whole exterior of the truck, including the top, and the floor of the interior. I didn't go up the walls on the inside rear 1/4 panels, but you might be able to stretch it to make it work.
-Wear gloves. Buy a box of disposable gloves (cheap at Harbor Freight) and keep them on. It's really hard to remove the paint, especially Chassis Saver, from your skin.
-I used my garage and left the door open except when the sun was shining in the morning (when I left it open halfway) since you're not supposed to use the paint on metal in direct sun. Had no problem with ventilation and smell though I did have a headache after painting all day on both days I painted. Probably a combination of fumes and fatigue.
-Tape anything you don't want to get paint on. Including windshield and rear top seals- I thought I'd be able to control the roller but the paint has a tendency to splatter.
-If you do two colors like I did I would recommend putting a good amount of time between the two colors. I painted the white on a Monday and a red on a Tuesday. The problem that I ran into was that when painting red, anytime that a little red paint got onto the white, which is going to happen, when I wiped the white section with acetone it wasn't dry enough and the acetone took off some of the white paint. I had to go back over each of theses patches later with white to fill in the texture and fix the color. I would recommend doing one color on a Saturday and then doing the other color the next Saturday, but that would put your truck out of commission for a couple weeks.
If you've got any other questions I'd be glad to answer them, but these are just the things off the top of my head I wish I'd known before starting.