Slovak is written as it sounds, and isn't as difficult as it looks. It may help to remember that Slovak makes use of only four diacritical marks, which are basically the same ones as in Czech except that the tongue-twisting "ř" (pronounced like an "rzh") and ů. The most common are: é, which lengthens a vowel ( does not imply stress), and ď, which softens a consonant. The palatisation is occasionally used in Czech, but is more widely used in Slovak
Like Czech, stress in Slovak usually falls on the first syllable, but try not to exaggerate it as it would be in English or in German.