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Ionic compounds involve ions, so they are typically the combination of a metal and a nonmetal, such as NaCl, CaBr2, AlCl3, etc. Some ions that are made completely of nonmetal can form ionic compounds. The main example is the ammonium ion, NH4+, so when you find anything with NH4X, where X = Cl, Br, I, NO3, etc, they are also ionic compounds. The NH4+ is sometimes called a pseudo alkali metal ion, since it behaves as an alkali metal ion, hence, its name, ammonium, same ending as for alkali metals, lithium, sodium, potassium, etc.
Molecular compounds always involve two nonmetals, CO, CO2, NH3, N2O4, etc. That is how you can identify them easily, the bonding does not involve ions at all, so they are nonconductors of electricity under any circumstance, unlike ionic compounds that conduct electricity when dissolved in water or when molten. All hydrocarbons are molecular compounds for the most part, alkanes CnH2n+2 (CH4, C2H6, C3H8) and their derivatives, CH3Cl, C2H5Cl, and so on.
For acids, they must have at least one hydrogen atom covalently bonded to a rather electronegative elements, such as F, Cl, Br, or O. HF, HCl, HBr, HI, are binary acids. Other types of acids are the oxyacids, they contain oxygen and the hydrogen is bonded to the oxygen atoms in the molecule. The oxygen atoms are bonded to the nonmetal in the compound. Examples, HClO4 (perchloric acid), HNO3 (nitric acid), H2SO4, (sulfuric acid) and so on. To indicate the number of acidic protons in those acids, they are written first, so HClO4 (one acidic proton), H2SO4 (two acidic protons), H3PO4 (phosphoric acid, three acidic protons). When the compound has more than one type of hydrogen atoms (acidic vs. nonacidic), they are separated, so acetic acid becomes HC2H3O2 (the single proton is acidic, is bonded to the oxygen atom, the other three are nonacidic, they are bonded to one of the carbon atoms). This can be indicated in the following form as well: CH3COOH, from this formula you see the two different type of hydrogen atoms in this molecule.
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