Building a resin model or miniature is a little different from building metal or plastic minis but it's not something to be concerned about, you just need to take your time and a little more care than you would normally to avoid damage.
Examine each part carefully. Most of the part will have extra pieces of resin because of the casting process and these need to be sawn off with a razor saw - which is just a very fine saw. Saw them off carefully.
Some parts may also have mould-lines but these are easily removed. Using a craft knife scrape the mould line away bit by bit. Take care to make sure that you only scrape away the mould lines and not hard to replace detail. And mind your fingers...
Sand the area that had a mould line with wet and dry sandpaper, grade 600 or smoother.
Polish the area with synthetic wire wool.
Be patient, don't try to remove too much material at once and stick with it. Getting a really good finish that's easy to paint on is quite achievable.
There will probably be some small holes left by tiny air bubbles in some of the parts. The really small holes can easily be filled with a drop of super clue and then made invisible by sanding the area. The larger holes (large means more than 2mm here, so not very big) will need filling with epoxy putty and sanding when it's gone hard - Green Stuff, Milliput or something similar.
Fit the model together WITHOUT GLUE, file and trim where needed to get a good fit.
You might want to leave some parts unassembled to make them easy to paint - now's the time to think about this and not when you realise you can't get a brush in there....
Wash the model, warm soapy water, gently. Make sure it's completely dry.
Use Super Glue to assemble the parts you've decided to build at this stage.
No one gets it right all of the time and expoxy putty will probably get you out of a good number of problems at first.
Have fun though.