Trailhead has over 1,000 modules. The challenge isn't finding content — it's knowing what order makes sense and what actually prepares you for the Platform Developer I exam (and real project work). Here's the path that works.
Who This Is For
- Developers with programming experience (any language) new to Salesforce
- Admins transitioning to development roles
- Platform Developer I candidates who want structured prep
Time estimate: 120–160 hours of focused study + hands-on practice in a dev org
Phase 1 — Salesforce Fundamentals (Weeks 1–2)
Before writing a line of Apex, understand the platform:
| Module | Trail | Why It Matters | |--------|-------|---------------| | Salesforce Platform Basics | Get Started with Salesforce Platform | Mental model of the platform | | Data Modeling | Data Modeling | Objects, fields, relationships | | Salesforce User Management | Admin Beginner | Profiles, permission sets, orgs | | Reports and Dashboards | Reports & Dashboards for Lightning | Understanding data visibility |
Practice in dev org:
- Create a custom object with 5+ fields
- Set up a lookup relationship between two custom objects
- Build a basic report showing records from your custom object
Phase 2 — Apex Fundamentals (Weeks 3–5)
Apex Basics & Database
→ Apex Triggers
→ Apex Testing
→ Asynchronous Apex
Apex Basics — focus on:
- SOQL vs. SOSL (when to use each)
- DML operations (insert, update, upsert, delete)
- Governor limits — memorize the key ones
- Collections: List, Set, Map (and when each applies)
Key code pattern to master:
// Bulkified trigger handler — this pattern appears everywhere
public class AccountHandler {
public static void handleBeforeInsert(List<Account> newAccounts) {
// Collect data first (no DML in loops)
Set<String> domains = new Set<String>();
for (Account acc : newAccounts) {
if (acc.Website != null) {
domains.add(acc.Website.toLowerCase());
}
}
// One query for all records (not N+1)
Map<String, List<Contact>> existingByDomain = new Map<String, List<Contact>>();
for (Contact c : [SELECT Id, Email FROM Contact WHERE Email != null]) {
String domain = c.Email.substringAfter('@').toLowerCase();
if (!existingByDomain.containsKey(domain)) {
existingByDomain.put(domain, new List<Contact>());
}
existingByDomain.get(domain).add(c);
}
// Process
for (Account acc : newAccounts) {
if (acc.Website != null) {
List<Contact> matches = existingByDomain.get(acc.Website.toLowerCase());
if (matches != null && !matches.isEmpty()) {
acc.Rating = 'Hot';
}
}
}
}
}Trailhead modules:
- Apex Basics & Database
- Apex Triggers
- Apex Testing
- Asynchronous Apex (future, batch, queueable, scheduled)
Phase 3 — Visualforce and LWC (Weeks 6–8)
The exam still tests Visualforce basics. Don't skip it.
Visualforce — minimum viable knowledge:
<apex:page>,<apex:form>,<apex:inputField>,<apex:commandButton>- Standard controllers vs. custom controllers
- View state and its limits
- When Visualforce is still appropriate (email templates, PDF generation)
LWC — this is the present and future:
Lightning Web Components Basics
→ Build a Bear Force One (hands-on project)
→ LWC and Salesforce Data
→ Lightning Web Components Specialist Superbadge
The Superbadge is 6–10 hours but worth every minute. It's the closest Trailhead gets to real project work.
Phase 4 — Integration and Security (Weeks 9–10)
Apex Integration Services
→ REST API Basics
→ Salesforce Security Basics
→ Identity and Access Management Architect (selective modules)
Focus areas:
- REST and SOAP callouts from Apex
- Named Credentials (tested on the exam)
- HttpCalloutMock for testing callouts
- OAuth flows (user-agent, web server, JWT bearer)
- Profiles vs. Permission Sets vs. Sharing (see the security model article)
Phase 5 — Exam Prep (Weeks 11–12)
Official study materials:
- Platform Developer I Study Guide — download the PDF, it lists exact exam topics
- Focus Trailmix: Platform Developer I Exam Preparation
Exam topic weights:
Salesforce Fundamentals: 7%
Process Automation and Logic: 38% ← heaviest section
User Interface: 25%
Testing, Debugging, Deployment: 17%
Integration and Data Management: 13%
Practice exams:
- Trailhead Trailmix for PDI has practice questions
- Focus on scenario-based questions (not trivia)
- Study the "why" behind governor limits, not just the numbers
Dev Org Practice Projects
Don't just do Trailhead badges. Build real things:
- Case escalation system — trigger that updates a case to high priority after 48h, sends email
- Contact deduplication — batch job that merges duplicate contacts by email
- External API integration — callout to a public REST API (weather, currency), display results in LWC
- Custom permission-based UI — LWC that shows different content based on a custom permission
Common Mistakes
- Doing badges without a dev org: Trailhead playgrounds reset — use a persistent dev org for your projects
- Skipping the Superbadge: it surfaces gaps in knowledge that badges don't
- Memorizing without understanding: the PDI exam tests scenarios, not syntax recall
- Ignoring test coverage quality: the exam specifically asks about TestDataFactory,
@TestSetup, and meaningful assertions
