Some basic questions about scenery

Cheap car primer, PVA glue and YouTube are your main tools. Look up the terrain tutor and lukeAPS for a start.

Painting mdf if it's sealed isn't a problem, but the burnt edges can act like a sponge and soak up tonnes of paint, you can seal it yourself with PVA, let it dry then a couple of coats of the car primer will give you a good base to work with.

Model paint (Vallejo, p3, army painter etc) will all work fine for resin bits, but using them on big things can get expensive very quickly. Artist acrylics can work out a lot better on buildings and such.

 

My suggestion about Scenery 101: pick 1-3 sets of cardboard scenery from CB, the Lotus one offers the best size variation, and you can print the containers from the PDF Corvus has in their downloads page (it's a Maglev PDF, however only the first bunch of pages are the Maglev "map", the rest are containers). Then go to Topo Solitario's webpage for some variation, and finally get some of Tommygun's extras (I'm quite "addicted" to his riveted deposit, I've succesfuly used it for more than just Pringles tubes).

Once you did that, going for MDF scenery demands PVA glue, but I suggest you also use some hot glue to reinforce some parts from the underside (also, real life terraces tend to accumulate stuff in corners, so...). As for painting, be careful since MDF is VERY porous, a sealing "priming" will be needed (use a spray of the base color, however), after which you can add some details and paste some printed posters for example.

 

A good way to seal MDF scenery for painting is to use an enamel based primer. Will save you having to use PVA which can swell joints and gives a good base layer for painting on.

 

If you've got a decently ventilated area, Zinsser's shellac is great for sealing MDF. Antenociti recommends the white but clear works fine for me.

 

I will answer in the first and more important word of High Gallego: It Depends.

Microarts' and other official partners require to be primed before being painted. However, there are some plastic/resin miniatures and scenery that not only do not require priming, but the priming won't cure 100% ever (it happens with Reaper Miniatures, for example); it is better to look it in google "[company name] [Resin/plastic] priming" for example.

 

This depends really more on the primer then anything else. Enamel based primers won't work (most spray can primers) on say Reaper but paint on or airbrush primers will work just fine. That being said if unsure it's better to be safe then sorry and ask or google as Xagroth said.

As for varnish it depends on the material. PVC stuff like Reaper Bones don't need it on the softer stuff but do for the harder terrain pieces. The purpose of a varnish are 2 fold:

1) Protect against oil in the skin. This is the main reason paint eventually comes off of metal figures, just touching them will weaken the paint and over time will flake\chip\wear. Varnish will help protect against this.

2) friction wear. This is just setting something, like a figure on a base, on the paint and moving it around. That can scratch\damage the paint. Varnish will also protect against that as well.

Gloss and satin are way more durable\stronger protection then dull which really doesn't offer much which is why you see people spray gloss first then dull it.

As for sealing MDF both spray can primer (Enamal) and Shellac are great for it. Shellac is sandable so that's awesome but its thicker and expensive out of a spray can and I don't care to brush it so I do rattle cans almost exclusively now as you can just pic a color from a huge range (look into street art spray cans if the cheaper brands don't have what you want) and make that your undercoat\base coat (depending on your paint style) and it saves you a lot of time.