Step 1: Identify what is given (sides, angles, area, radii) and what is asked. Step 2: Select the appropriate formula — sine rule for ASA/AAS, cosine rule for SAS/SSS, area formula for SAS with area, half-angle formulas when sides are given and angle half-values are needed. Step 3: For identity proofs, try expressing all sides in terms of angles using a = 2R sinA, or all angles in terms of sides using the cosine rule. Step 4: For inradius/exradius problems, use Delta = rs and $\frac{Delta}{s-a}$ = r1. Step 5: Check if the problem involves conditional identities (A + B + C = pi). Step 6: For numerical problems, compute the semi-perimeter first, then the area via Heron's formula, then derive other quantities. Always verify that your triangle satisfies the triangle inequality.