Self sealing bike tubes work great for tiny holes caused by small thorns or other sharps. I have been using them for years with my mountain bike. I change tubes about once per year and can see all the holes that have been filed and sealed.
I used to get a flat tire once per month but since I switched to tubes with sealant I can go 6 months without a flat.
Once thing to note is that they will not repair a major hole like if you hit a nail.
They cost less than $10 each and last me a year. They are available at retailers and online stores. I highly recommend you install them to spend less time fixing flats and more time riding.
You should check everything on a regular basis and do complete tune-up once per year. Maintenance of mountain bikes is important because they tend to wear out sooner than expected, as they are subjected to all kinds of harsh weather and rough terrains.