@Aaryan Patel things I wish I had done when I first started:
-learn more about what impacts DTI, and how that impacts borrowing ability (and learn to plan accordingly).
-screen potential tenants more carefully, and be more willing to not rent to tenants who present red flags (when you're first starting out, you're usually desperate to get rent income, and this can easily lead you to turn a blind eye to tenant issues that you should be paying more attention to).
-use a more professional system of accounting (designed with guidance from a CPA who understands real estate).
-get a CPA who understands real estate.
Things that I DID do when starting out that I think were critical for success:
-find an agent with extensive first-hand experience maintaining and managing their own rental properties (someone who actually can swing a hammer and fix basic plumbing problems), and who is excellent at evaluating a property for potential issues before you make an offer. It's also critical that this agent acts as a true fiduciary and is willing to steer you away from a bad deal (even if it means they lose a commission in the process). Build a relationship with that agent over many years and many deals, and they will become a valuable partner.
-find a mortgage broker who is bluntly honest, conservative with their quotes, and highly experienced with a wide range of products that investors often use (i.e.; investment mortgages, cash-out refis, etc.). Again, build a relationship with that broker over many years and many deals--it will pay dividends.
-before you even make an offer, spend significant time under the house, in the attic, in other utility areas, and around the house looking for potential problems. Your due diligence process should start the moment you and your agent see the property, and should not rest solely on the inspector. If you don't know how to spot problems, have an agent who does, or pay a contractor to come with you. Personally, I spend significant time looking for foundation issues, significant settling or structural issues, and indicators of previous flooding (particularly flooding caused by groundwater rising up from underneath the slab)--these issues are usually deal-breakers for me. I also pay close attention to the windows, doors, electric, plumbing and HVAC (though, I am more willing to take on properties with issues in these areas if the price of the property is right). ...it's no fun to cancel a contract because your inspector finds serious structural issues that you could have easily spotted at the outset if you had just spent 10 minutes looking around under the house...
-find an inspector who is thorough and trustworthy, and who is willing to answer many questions.
-do not speculate on future appreciation, and do not commit to a plan that requires future appreciation to pencil out. Particularly when you're starting, the property must cashflow adequately to protect you against worst-case-scenario events. You also want to target appreciation, but if the house doesn't cashflow adequately, it should be a deal-breaker.
-every time you have a positive experience with any professional who helps you with the property (e.g.; electricians, landscapers, property managers, plumbers, roofers, etc., etc.), save their contact info to build a rolodex of dozens of support personnel...this is your team, and much of your success or failure can hinge on their competence. You'll need their help again (eventually), and your goal is to build a relationship where you are their favorite customer, and therefore their top priority when things turn south.
-house hack--which comes with many, many benefits for a new investor (it's a relatively low-stakes way to get a property, and it's "training wheels" for learning how to be a landlord and successfully manage a rental...it also comes with owner occupant mortgage terms, which are the best. Overall, it's arguably the best strategy for a newbie to start investing in RE).
-buy a property with multiple possible uses and exit strategies, do not buy a property that depends solely on a single course of action to pan out. For instance, if a property could work as a LTR, MTR, STR, a flip, a BRRRR, a forced rent appreciation through value add, OR a personal residence that you'd be happy with, those are a lot of options....but if the property ONLY works as a STR (or ONLY works as some other thing), then you could be painting yourself into a corner.
-know what type of property you're looking for, but ALSO be flexible. We're often told that we need to have clear selection criteria, and this is true to an extent...however, in today's market, it also helps to be flexible enough to look at, and buy a property that has some fairly inconsequential issue that turns off other buyers (putting you in a better position for a deal). Nearly every single property I have came with some quirk that turned off other buyers, but that was largely inconsequential to my plans (for instance, an oddly-placed staircase, ugly old carpet, a location that was on a somewhat busier street, etc.)...if I had absolutely strict, inflexible criteria, I might not have looked at those properties.
-use a highly specific, professionally-designed lease customized to the specific properties that provides the absolute most protection from all the liabilities that come from renting a property. My current lease is over 30 pages (single spaced), and covers virtually any event imaginable. Excessive? Maybe. But when problems arise, I'm always happy that my lease protects me, and/or allows me to deal with those problems.
-build adequate protection via an LLC and/or an appropriate level of liability insurance (personally, I use both).
-don't bite off more than you can chew...base decisions on conservative financial models, don't try to buy a property that's way outside your financial capacity, or that would involve management headaches that you're not equipped to deal with...start small, and gradually build to larger and/or more complex strategies (as your finances and your expertise improve)... don't try to syndicate rehab flip a 50 unit D-class portfolio on the other side of the country for your first deal (unless you enjoy the extra spicy sensation of a new ulcer). Learn to walk before you try to ice skate in the Olympics.
Good luck out there!